Developer, are you (unconsciously) developing sites for users just like yourself? It often means a sighted mouse user with good fine motor skills and who is proficient with computers. But not every user is like that.
Many projects have automated accessibility checkers, and that is a good start. However, they don't catch most of the failures on accessibility. There are some fairly simple checks to ensure a better experience for your users, and from this talk, you'll learn how to do them and, most importantly, why they are essential to do.