There is an all-in-one article including every part from this series (if you want prefer to read it all at once instead of "by installments")
We often hear this term when a project is at an advanced stage and not accessible. "Accessibility is difficult!" As if it was a justifiable reason because of all the delays they are experiencing.
But there's nothing further from the truth. Accessibility is not difficult. Do you know what's difficult? Running at an Olympic level. Even more, just running is difficult. A baby needs 12 months to start crawling, walking, and finally running. It's a slow process that requires strengthening the muscles, getting coordination, practice, practice, and more practice.
On the other hand, a Web Developer can learn at least the basics of Web Accessibility within hours, practice within days, and have a good grasp within weeks. Of course, they won't be experts. Still, they would be able to fix and prevent many of the issues highlighted in the WebAIM Million report and avoid the main accessibility issues that plague the Internet nowadays.
Obviously, there are more things to Web Accessibility than just the basics. Learning and mastering more advanced approaches takes time, but a good enough level is possible within a reasonable time.