Derek gives Chris a rundown on a11y, aka web accessibility. Tune in to the learn why accessibility matters for all apps, how to approach it, and what tools are available to help on the journey.
Speaking from experience while accessibility is super important, trying to get certain parts of a non-trivial web application to be accessible (especially when parts of your application change via javascript. Example: Giving focus to a modal popup and/or form errors) can be rather time consuming. Part of this is because all screen readers are not the same (kinda like web browsers). So you may get something working correctly in one screenreader meanwhile it doesn’t work well in another.
Also JAWS (the most popular screen reader on Windows) is not developer friendly: WebAIM: JAWS license not developer friendly. ChromeVox (the free screenreader for Chrome http://www.chromevox.com/) seems to be similar to JAWS at least.
There’s a minor inaccuracy in this video and notes: “there is no <main> element we can use”. There is now a <main> element, maybe it was introduced after this video was released. Not necessarily all screen readers support it, though, so it’s important to use both the element and role.