Skip to main content

Main navigation

  • Home
  • Discover
  • Learning Center
  • What’s New

Second main navigation

  • Altium Community
  • Support
  • Documentation
×

Results

  • Updates
  • Blog 570
  • Video 539
  • Webinar 86
  • Playlist 53
Filters:
Tag (field_common_tag)
 Preventing Obsolescence Before It Hits
On-Demand Webinar • Jun 12, 2025
Proactive Lifecycle Management: Preventing Obsolescence Before It Hits
Take the first step toward eliminating avoidable delays and costly redesigns. Don't miss it and register now!
Watch Now
Integrating Requirements June 2025 Webinar
On-Demand Webinar • May 28, 2025
Integrating Requirements into Your PCB Design Workflow
Join our webinar where you will learn about integrated requirements tools who can help you eliminate late-stage design changes, AI support through system requirements and integration of design requirements directly in PCB Design. Don't miss it, register now!
Watch Now
A365 Webinar
On-Demand Webinar • Apr 23, 2025
Collaborative Design Review: Ensuring Quality from Schematics to Supply Chain
Join our live webinar to learn how Altium 365 accelerates collaboration, standardizes workflows, and ensures design integrity to mitigate risks and accelerate time to market.
Watch Now
Webinar: From Prototype to Production: Optimizing BOM Costs Without Compromising Quality with Part Analytics
On-Demand Webinar • Apr 22, 2025
From Prototype to Production: Optimizing BOM Costs Without Compromising Quality with Part Analytics
Learn how to reduce production BOM costs without redesign, explore techniques to consolidate part demand for volume savings, and discover case examples from supply chain teams that increased sourcing process efficiency by up to 97%.
Watch Now
Streamlining Team Collaboration
On-Demand Webinar • Apr 17, 2025
Streamlining Team Collaboration in Industrial PCB Projects
Join us for our upcoming webinar to discover how Altium Designer and Altium 365 can transform your team’s collaboration and take your PCB design projects to the next level. Attend for a chance to win free access to the Altium 365 Training Bundle.
Watch Now
Component management
On-Demand Webinar • Apr 10, 2025
Ensure Best Designs with Professional Library Management
In this webinar, you'll discover how Altium Designer facilitates robust component management, including adding part choices to mitigate supply chain risks and leveraging Altium 365 managed components.
Watch Now
April 2025 Webinar Cover
On-Demand Webinar • Apr 9, 2025
Component Selection in Altium Designer: Making Data-Driven Decisions with Data Integrations
Improve component selection with real-time data insights in Altium 365! Join our live webinar to optimize your PCB development. Sign up now!
Watch Now
NEW
Blog • Jan 15, 2026
Flexible Circuits: Enhancing Performance with Shielding, Heat Dissipation, and Stiffeners

A flex circuit can look perfect on paper and still fail in the real world due to EMI, hot spots, or mechanical strain. This article breaks down how shielding, thermal planning, and stiffeners help deliver designs that stay reliable over time.

Read More
NEW
Embedded thumbnail for Power Analyzer by Keysight Promo Video
How-To's • Jan 14, 2026
Power Analyzer by Keysight Promo Video

Unlock faster, more reliable PCB design with Altium Designer Agile Teams and Power Analyzer by Keysight. Integrated directly inside Altium Designer, this powerful combination enables fast, secure, and adaptive collaboration helping engineering teams move quickly, stay aligned, and scale confidently. Watch this short video to see how this software improves your PCB design process.

Start Watching
NEW
Blog • Jan 13, 2026
Avoid These Top 3 Power Distribution Failures in PCB Design

Power distribution issues can silently undermine your PCB’s reliability. This article uncovers the top three failure modes and shows how Power Analyzer by Keysight helps you catch them early in the design phase and how Altium Agile Teams turns those checks into structured team action.

Read More
NEW
Embedded thumbnail for Do 90-Degree Bends Destroy Signal Integrity? The Surprising Answer
How-To's • Jan 12, 2026
Do 90-Degree Bends Destroy Signal Integrity? The Surprising Answer

Discover why the long-held belief about 90-degree PCB traces may be more myth than reality. This video explains key signal integrity principles and uncovers insights that can help you make more informed design decisions.

Start Watching
Blog • Dec 11, 2025
From BOM to Requirements and Back: Building Sourcing Constraints Into Specs

When engineering and procurement remain disconnected, supply-chain problems will sneak up on you. This guide argues convincingly: embed sourcing constraints into your requirements from day one, and avoid costly rework down the line.

Read More
Embedded thumbnail for Taking Control Without Adding Complexity – Presentation Embedded World North America 2025
New in Altium Designer 20 • Dec 10, 2025
Taking Control Without Adding Complexity – Presentation Embedded World North America 2025

See how Altium makes project oversight faster and smarter with automated workflows, real-time tracking, and connected design data without adding work for engineers. Watch our Embedded World North America 2025 presentation to learn more.

Start Watching
Blog • Dec 9, 2025
Understanding Power Integrity in PCB Design: Power Analyzer by Keysight Whitepaper

Power integrity is the backbone of reliable PCB design. This whitepaper explains how to analyze and optimize voltage drop, current density, and grounding directly within Altium Designer Agile using the Power Analyzer by Keysight.

Read More
Embedded thumbnail for Demonstration Altium DISCOVER - Embedded World North America 2025
Embedded World 2025 • Dec 8, 2025
Demonstration Altium DISCOVER - Embedded World North America 2025

Check out our live demo from Embedded World North America 2025 showcasing Altium Discover. In this video, you’ll see how the platform helps reduce sourcing risk, shorten design cycles, and keep projects moving forward with confidence.

Start Watching
Blog • Dec 4, 2025
How to Manage ECAD Libraries for Consistent PCB Layout Design

Strong hardware starts with strong libraries. Discover how disciplined ECAD-library management dramatically improves design consistency and accelerates every stage of your PCB workflow.

Read More
  • Show More
Tag (field_common_tag)
MLCC controlled ESR capacitor
Blog • Oct 19, 2021
Controlled ESR Capacitors: Should You Use Them for Power Integrity?

I can’t think of a single product I’ve built that doesn’t require capacitors. We often talk a lot about effective series inductance (ESL) in capacitors and its effects on power integrity. What about effective series resistance (ESR)? Is there a technique you can use to determine the appropriate level of resistance, and can you use ESR to your advantage?

Read More
Ground Pour, Impedance and Losses
Blog • Oct 14, 2021
Microstrip Ground Clearance Part 2: How Clearance Affects Losses

If your goal is to hit a target impedance, and you’re worried about how nearby pour might affect impedance, you can get closer than the limits set by the 3W rule. But what are the effects on losses? If the reason for this question isn’t obvious, or if you’re not up-to-date on the finer points of transmission line design, then keep reading to see how nearby ground pour can affect losses in impedance-controlled interconnects.

Read More
Choosing the Right Microphone for Embedded Applications
Blog • Oct 12, 2021
Choosing the Right Microphone for Embedded Applications

If you need to capture sound waves for your electrical device to process, you'll need a microphone. However, microphones these days have become very advanced, and there are so many options to choose from. They range from the relatively simple and popular condenser type microphones to state-of-the-art sound conversion solutions incorporating internal amplifiers and other electronic processing functionality. In this article, we'll take a look at some of the options available.

Read More
 Computer planet with circuit grid
Blog • Oct 7, 2021
Composite Amplifiers and How They Give the Best of Both Worlds

There are many times where you need an amplifier with high gain, low noise, high slew rate, and broad bandwidth simultaneously. However, not all of these design goals are possible with all off-the-shelf components. Here are some points to consider when working with a composite amplifier design and how to evaluate your design with the right set of circuit simulation tools.

Read More
Impedance balancing power supply
Blog • Oct 5, 2021
Reduce Common-Mode Noise in Your Power Supply with Impedance Balancing

Simple switching regulator circuits that operate in compact spaces, like on a small PCB, can usually be deployed in noisy environments without superimposing significant noise on the output power level. As long as you lay out the board properly, you’ll probably only need a simple filter circuit to remove EMI on the inputs and outputs. As the regulator becomes larger, both physically and electrically, noise problems can become much more apparent, namely radiated EMI and conducted EMI in the PCB layout.

Read More
Part 1: Why Your PCB Design Review Process Is Obsolete and What You Can Do About It
Blog • Sep 28, 2021
Part 1: Why Your PCB Design Review Process Is Obsolete and What You Can Do About It

A PCB design review is a practice to review the design of a board for possible errors and issues at various stages of product development. It can range from a formal checklist with official sign-offs to a more free-form inspection of schematic drawings and PCB layouts. For this article, we will not delve into what to check during a design review process but rather look at how a review process itself usually unfolds and how to optimize it to get the most out of your time.

Read More
Part 2: Why Your PCB Design Review Process Is Obsolete and What You Can Do About It
Blog • Sep 27, 2021
Part 2: Why Your PCB Design Review Process Is Obsolete and What You Can Do About It

As we established in Part 1, the PCB design review and collaboration practices have room for improvement in many organizations. To address this, we developed Altium 365. Let's examine how running a PCB project through Altium 365 compares to other methods.

Read More
Star ground PCB
Blog • Sep 23, 2021
What is PCB Star Grounding and Why Would Anyone Use It?

If you look on the internet, you'll find some interesting grounding recommendations, and sometimes terminology gets thrown around and applied to a PCB without the proper context or understanding of real electrical behavior. DC recommendations get applied to AC, low current gets applied to high current, and vice versa... the list goes on. One of the more interesting grounding techniques you'll see as a recommendation, including on some popular engineering blogs within the industry, is the use of PCB star grounding.

Read More
Silkscreen on PCB
Blog • Sep 21, 2021
Your Guide to PCB Silkscreen

Every PCB has silkscreen on the surface layer, and you’ll see a range of alphanumeric codes, numbers, markings, and logos on PCB silkscreen. What exactly does it all mean, and what specifically should you include in your silkscreen layer? All designs are different, but there are some common pieces of information that will appear in any silkscreen in order to aid assembly, testing, debug, and traceability

Read More
Gibbs ringing
Blog • Sep 16, 2021
What Causes Gibbs Ringing in High-speed Channel Simulations?

Designing high-speed channels on complex boards requires simulations, measurements on test boards, or both to ensure the design operates as you intend. Gibbs ringing is one of these effects that can occur when calculating a channel’s response using band-limited network parameters. Just as is the case in measurements, Gibbs ringing can occur in channel simulations due to the fact that network parameters are typically band-limited.

Read More
Heated component on PCB
Blog • Sep 14, 2021
Efficient Heat Dissipation with SMD Heat Sinks Keeps You From Dropping PCBs

In electronics, there is the possibility that your PCB can get pretty hot due to power dissipation in certain components. There are many things to consider when dealing with heat in your board, and it starts with determining power dissipation in your design during schematic capture. If you happen to be operating within safe limits in a high power device, you might need an SMD heat sink on certain components. Ultimately, this could save your components, your product, and even the operator.

Read More
RF PCB
Blog • Sep 9, 2021
RF Power Supply Design and Layout Guide

One thing is certain: power supply designs can get much more complex than simply routing DC power lines to your components. RF power supply designs require special care to ensure they will function without transferring excessive noise between portions of the system, something that is made more difficult due to the high power levels involved. In addition to careful layout, circuitry needs to be designed such that the system provides highly efficient power conversion and delivery to each subsection of the system.

Read More
Prevent Overvoltage, Overcurrent and Heat logo
Blog • Sep 7, 2021
Methods to Protect your Circuit

Overvoltage, overcurrent, and heat are the three most likely events that can destroy our expensive silicon-based components or reduce our product’s life expectancy. The effects are often quite instant, but our product might survive several months of chronic overstress before giving up the ghost in some cases. Without adequate protection, our circuit can be vulnerable to damage, so what should we do? Or do we need to do anything?

Read More
SUBCKT sharing
Blog • Sep 2, 2021
SUBCKT Sharing: The Fastest Ways to Share SPICE Models Online

Today’s PCB designers and layout engineers often need to put on their simulation hat to learn more about the products they build. When you need to perform simulations, you need models for components, and simulation models often need to be shared with other team members at the project level or component level. What’s the best way for Altium Designer users to share this data? Read this article to learn more about sharing your models with other design participants. 

Read More
RF Printed Circuit Board
Blog • Aug 31, 2021
RF PCB Material Comparison for mmWave Devices

When some designers start talking materials, they probably default to FR4 laminates. The reality is there are many FR4 materials, each with relatively similar structure and a range of material property values. Designs on FR4 are quite different from those encountered at the low GHz range and mmWave frequencies. So what exactly changes at high frequencies, and what makes these materials different? To see just what makes a specific laminate useful as an RF PCB material, take a look at our guide below. 

Read More
Testing Challenges and Solutions
Blog • Aug 26, 2021
Low Cost Solutions for Automated Hardware in the Loop Testing

In today’s fast-paced world where iterations of electronics are spun at lightning speeds, we often forget one of the most critical aspects of development: testing. Even if we have that fancy test team, are we really able to utilize them for every modification, every small and insignificant change that we make to our prototypes? In this article, we will review a very low cost, yet highly effective and quite exhaustive test system that will get you that bang for your buck that you’ve been looking for.

Read More
  • Show More
Tag (field_common_tag)
Embedded thumbnail for Pi Filter Formulas and Simulation Deep Dive
How-To's • Dec 13, 2024
Pi Filter Formulas and Simulation Deep Dive

Learn the essentials of Pi filters, including how to size, design, and simulate them in Altium Designer. Host Zach Peterson explains the design equations for Pi filters, discusses online tools for accurate component selection, and demonstrates real-time simulations in Altium Designer to visualize the effects of impedance mismatches.

Start Watching
Embedded thumbnail for True Donut Pad Shapes
New in Altium Designer 25 • Dec 11, 2024
True Donut Pad Shapes

Check out our brand-new short video showcasing an exciting improvement in the PCB design process. Altium Designer 25 now supports true donut pad shapes, enhancing both your routing and performance.

Start Watching
Embedded thumbnail for Modernizing Engineering Workflows: Altium Designer 25 and the Future of Concurrent Design - Recording Preview
New in Altium Designer 25 • Dec 10, 2024
Modernizing Engineering Workflows: Altium Designer 25 and the Future of Concurrent Design - Recording Preview

Discover the new features in Altium Designer 25! This webinar recording highlights the Signal Analyzer by Keysight, advanced Wire Bonding capabilities, multi-board design enhancements, and more, showcasing how these tools can transform your PCB design process.

Start Watching
Embedded thumbnail for Dynamic Phase Matching and Tuning for Differential Pairs
New in Altium Designer 25 • Dec 5, 2024
Dynamic Phase Matching and Tuning for Differential Pairs

Explore how dynamic phase matching for differential pairs works with the improved match length rule in Altium Designer. Learn key techniques in this quick tutorial!

Start Watching
Embedded thumbnail for Obey Rules and Auto-Shrinking Features
New in Altium Designer 25 • Dec 4, 2024
Obey Rules and Auto-Shrinking Features

Discover how Altium Designer 25's Obey Rules and Auto-Shrinking features streamline routing, ensuring speed and precision while maintaining adherence to all design constraints.

Start Watching
Embedded thumbnail for Quickstart Guide: Single Layer PCB Design with Altium Designer 25
New in Altium Designer 25 • Nov 27, 2024
Quickstart Guide: Single Layer PCB Design with Altium Designer 25

Transform your designs with the new Single Layer PCB Design feature in Altium Designer 25! Whether you're working on Rigid-Flex projects or creating simple, space-saving boards, this tool makes the process faster, smarter, and more efficient. Watch our guide now and unlock your next big innovation.

Start Watching
Embedded thumbnail for How to Design Bending Regions in Flex PCBs
How-To's • Nov 25, 2024
How to Design Bending Regions in Flex PCBs

Watch our latest video on bending regions in flex PCBs! This step-by-step guide will show you how to configure stack-ups, distinguish between flex and rigid regions, and troubleshoot common issues in 3D views.

Start Watching
Embedded thumbnail for LDO Regulator Essentials: From Basics to Advanced. Part V: Ripple Rejection
LDO Regulator Essentials • Nov 22, 2024
LDO Regulator Essentials: From Basics to Advanced. Part V: Ripple Rejection

The final part of the LDO Regulator Essentials series focuses on voltage ripple rejection in Low Dropout Regulators (LDOs). Our host Rafał Stępień explains how LDOs clean up DC supply waves, ensuring stable performance in power systems. This episode provides practical insights for optimizing sensitive designs.

Start Watching
Embedded thumbnail for Explore Routing Improvements in Altium Designer 25
New in Altium Designer 25 • Nov 21, 2024
Explore Routing Improvements in Altium Designer 25

Discover Routing Improvements in Altium Designer 25. Learn about Dynamic Phase Matching, True Donut Pad Shape, and more in our latest video showcasing the powerful enhancements in our newest release.

Start Watching
Embedded thumbnail for Join our upcoming webinar and WIN Free Training!
New in Altium Designer 25 • Nov 19, 2024
Join our upcoming webinar and WIN Free Training!

Don't miss the chance to win FREE access to Mixed Simulation On-Demand Training! Be a part of our webinar on November 21 for our webinar, Modernizing Engineering Workflows: Altium Designer 25 and the Future of Concurrent Design. Register here: AD25 Webinar Registration Page. 

Start Watching
Embedded thumbnail for Wire Bonding Shorts: Die Footprints
New in Altium Designer 25 • Nov 18, 2024
Wire Bonding Shorts: Die Footprints

Check our new short video where Samer Aldhaher demonstrates the Wire Bonding feature in Altium Designer 25, including die-to-die and die-to-copper connections, multiple wire bonds, and pad rotation techniques.

Start Watching
Embedded thumbnail for Altium Designer 25: Collaboration at its Finest
New in Altium Designer 25 • Nov 13, 2024
Altium Designer 25: Collaboration at its Finest

Altium Designer 25 focuses on enhancing collaboration for engineering teams with new tools like the SI Analyzer by Keysight, updated PCB CoDesign, MCAD and Ansys CoDesigners, and improved Simulation modules. This release also introduces Wire Bonding, Single Layer PCB, and performance upgrades for optimized PCB design workflows. Check our overview video about all the improvements in this release.

Start Watching
Embedded thumbnail for The Fastest Ways to Run a PCB BOM Review
How-To's • Nov 12, 2024
The Fastest Ways to Run a PCB BOM Review

Conducting a BOM review is crucial to prevent costly delays, obsolete components, and unforeseen sourcing challenges in your PCB project. Discover powerful tools like DigiKey, Octopart, and Altium 365’s BOM portal to simplify your review process and ensure you're selecting the best parts at optimal prices.

Start Watching
Embedded thumbnail for Quantum Systems uses Altium Designer and Altium 365 to build the future of Drones
Altium Stories • Nov 6, 2024
Quantum Systems uses Altium Designer and Altium 365 to build the future of Drones

Quantum Systems creates advanced drones for critical aerial intelligence across industries. With Altium Designer and Altium 365, they streamline electronics engineering and enhance team collaboration. Watch how Altium software helps them innovate faster and build reliable drones for mission-critical moments.

Start Watching
Embedded thumbnail for Wire Bonding Shorts: 3D Stacked Die with Cavity
New in Altium Designer 25 • Nov 5, 2024
Wire Bonding Shorts: 3D Stacked Die with Cavity

Check our short video by Samer Aldhaher on using Altium Designer’s wire bonding tool for creating 3D stacked die in cavity. Highlights advanced techniques for compact, high-performance PCB designs with 3D integrated circuits.

Start Watching
Embedded thumbnail for Constraint Manager Improvements in Altium Designer 25
New in Altium Designer 25 • Nov 4, 2024
Constraint Manager Improvements in Altium Designer 25

Discover the latest in Altium Designer 25’s Constraint Manager, with updates like flexible net selection, streamlined rule management, and differential pair handling. Simplify your PCB design workflow with powerful new tools and enhancements.

Start Watching
  • Show More
Tag (field_common_tag)
 Preventing Obsolescence Before It Hits
On-Demand Webinar • Jun 12, 2025
Proactive Lifecycle Management: Preventing Obsolescence Before It Hits
Take the first step toward eliminating avoidable delays and costly redesigns. Don't miss it and register now!
Watch Now
Integrating Requirements June 2025 Webinar
On-Demand Webinar • May 28, 2025
Integrating Requirements into Your PCB Design Workflow
Join our webinar where you will learn about integrated requirements tools who can help you eliminate late-stage design changes, AI support through system requirements and integration of design requirements directly in PCB Design. Don't miss it, register now!
Watch Now
A365 Webinar
On-Demand Webinar • Apr 23, 2025
Collaborative Design Review: Ensuring Quality from Schematics to Supply Chain
Join our live webinar to learn how Altium 365 accelerates collaboration, standardizes workflows, and ensures design integrity to mitigate risks and accelerate time to market.
Watch Now
Webinar: From Prototype to Production: Optimizing BOM Costs Without Compromising Quality with Part Analytics
On-Demand Webinar • Apr 22, 2025
From Prototype to Production: Optimizing BOM Costs Without Compromising Quality with Part Analytics
Learn how to reduce production BOM costs without redesign, explore techniques to consolidate part demand for volume savings, and discover case examples from supply chain teams that increased sourcing process efficiency by up to 97%.
Watch Now
Streamlining Team Collaboration
On-Demand Webinar • Apr 17, 2025
Streamlining Team Collaboration in Industrial PCB Projects
Join us for our upcoming webinar to discover how Altium Designer and Altium 365 can transform your team’s collaboration and take your PCB design projects to the next level. Attend for a chance to win free access to the Altium 365 Training Bundle.
Watch Now
Component management
On-Demand Webinar • Apr 10, 2025
Ensure Best Designs with Professional Library Management
In this webinar, you'll discover how Altium Designer facilitates robust component management, including adding part choices to mitigate supply chain risks and leveraging Altium 365 managed components.
Watch Now
April 2025 Webinar Cover
On-Demand Webinar • Apr 9, 2025
Component Selection in Altium Designer: Making Data-Driven Decisions with Data Integrations
Improve component selection with real-time data insights in Altium 365! Join our live webinar to optimize your PCB development. Sign up now!
Watch Now
Altium Agile
Live Webinar
Altium Agile Teams - Sneak Peek
Get a first glimpse into this new Electronic Product Development Platform.
Jan
21
English
3:00 PM, CET
Jan
21
German
10:00 AM, CET
Jan
22
Italian
10:00 AM, CET
Jan
22
French
3:00 PM, CET
Jan
22
Spanish
3:00 PM, CET
Register Now
Altium Designer Overview
On-Demand Webinar • Dec 4, 2025
Altium Designer Onboarding Workshop
Join our live training workshop and see Altium Designer in action—from creating your first schematic to delivering ready-to-manufacture PCB files.
Watch Now
Altium Platform
On-Demand Webinar • Nov 21, 2025
Altium Platform - A foundation to meet your & your company’s targets
Discover how the Altium platform makes multidisciplinary cooperation easy and efficient.
Watch Now
Harness design
On-Demand Webinar • Nov 17, 2025
From single PCB to Harnessed Product
Discover how to streamline PCB-to-harness design with Altium’s powerful tools and boost collaboration across disciplines.
Watch Now
3D-MID Design
On-Demand Webinar • Oct 20, 2025
3D-MID Design in Altium
Discover how even complex products for 3D circuit designs are implemented easily in Altium.
Watch Now
Altium Designer Overview
On-Demand Webinar • Aug 20, 2025
Altium Designer and Altium 365 Overview
In this webinar we will show you how easy it is to create a prototype from scratch using Altium Designer in combination with Altium 365.
Watch Now
Altium Enterprise
On-Demand Webinar • Aug 3, 2025
Safety & Reliability in Electronics Design – Strategies, Standards & Tools
How can development teams and decision-makers effectively implement safety, security, and compliance without delaying innovation?
Watch Now
Altium Enterprise
On-Demand Webinar • Aug 2, 2025
Sustainability & Energy Efficiency in Electronic Product Development
Watch Now
Proactive Component Selection
On-Demand Webinar • May 22, 2025
Proactive Component Selection: Mitigating Manufacturing Delays Before They Happen
Most teams spend hours on component research yet still face redesigns. Learn how Altium 365 helps you make proactive, data-driven part decisions. Join SiliconExpert’s Jackie Sartin to discover smarter sourcing with real-time insights and validated alternatives.
Watch Now
  • Show More
Tag (field_common_tag)
Tag (field_common_tag)
Loading
Loading...
Share link
Share with
Search by Update
Version
Update
25 26 24 23 22
25.0 25.1 25.2 25.3 25.4 25.5 25.6 25.7 25.8 25.9
26.1 26.2
24.10 24.9 24.8 24.7 24.6 24.5 24.4 24.3 24.2 24.1 24.0
23.11 23.10 23.9 23.8 23.7 23.6 23.5 23.4 23.3 23.2 23.1 23.0
22.11 22.10 22.9 22.8 22.7 22.6 22.5 22.4 22.3