If you’re just getting into accessibility (or a11y for short), or you’re getting comfortable with what you know and want to build on that, I recommend checking out the following resources.

Inclusive Design Principles

Principles for designing and developing user interfaces that will help you ensure people with permanent, temporary, situational, or changing disabilities are not excluded.
By: Henny Swan, Ian Pouncey, Heydon Pickering, Léonie Watson

a11y rules podcast: Conversations around web accessibility

A way to learn not just about accessibility, but the people that are accessibility advocates and practitioners.
By: Nicolas Steenhout

Webdev Newsletter & Weekly Roundup of Web Design and Development News

Weekly roundups of web resources, always including links to some of the best and latest accessibility related content being posted.
By: Laura Carlson & Deborah Edwards-Onoro, respectively

A11YTalks

A monthly virtual meetup that you can watch live, or later, talking about all things accessibility.
By: Many great speakers

The A11Y Project

Covering a range of entry to medium-level topics, The A11Y Project’s goal is to help people understand fundamental accessibility concepts.
By: The community

W3C WAI: Web Accessibility Tutorials

Covering a range of topics such as menus, general page structure and forms, these W3C hosted tutorials are a good place to learn some hows and whys to help build accessible web documents.
By: The W3C Web Accessibility Initiative

Inclusive Design 24 (#id24)

A free 24-hour online event that celebrates inclusive design and sharing knowledge and ideas. Past presentations are saved on their YouTube page.
By: Many great speakers

Inclusive Components

In depth looks at ways one might create inclusive versions of different popular UI components. The posts here served as the basis for the book published of the same name, with updated articles and new content.
By: Heydon Pickering

How to Meet WCAG (Quick Reference)

Use this resource to help you quickly parse through the various WCAG success criteria. Each entry links back to success criteria explainer, as well as linking directly to examples of techniques and failures.
By: The W3C Web Accessibility Initiative

A11y Style Guide

An open source example of how one might create a style guide that promotes accessibility through the explanation of the components within, and linking to WCAG criteria and other reference materials. Community involvement is welcome!
By: Carie Fisher

Accessibility Reviews

A community-driven resource to indicate the accessibility of various tools, services, platforms, and more.
By: Accessibility Reviews contributors

Empathy Prompts

Various prompts (exercises, situations, thoughts to noodle on) that are not intended to describe any one person’s experience, but challenge you to think about various situations in a way you’re maybe unaccustomed to.
By: Eric Bailey

Accessibility (a11y) Courses

A listing of paid and free courses offered in web accessibility (and other learning opportunities).
By Mike Gifford

Always more to learn

There are so many other great resources beyond the ones mentioned here. I suggest you let people know about some of your favorites, as well as the people who took the time to publish their work for the benefit of everyone.

Let’s keep learning.