Accessibility is about people. Web accessibility is about allowing people to use & understand your website without barriers. This talk covers the different types of cognitive and physical abilities that people have and how designers & developers create many unintended barriers to them using a website.
It talks about a number of practical matters, such as how to choose color palettes and what color combinations can cause barriers. It also discusses basic page structure and how that can make life easier or harder for people. It includes practical examples of websites and keyboard navigation through them.