A screen reader is a synthesizer that reads, in an electronic voice, what's on the screen to a person who is blind or partially sighted. If the website meets the WCAG standards, WCAG 3 or WCAG 2.0—I'm sorry, I don't know all the numbers in there—the website can be accessible with that. If there are some images there or some videos that are not described, or if they're set up so that the screen reader can't read what's on the screen or sometimes if there's imaging or programming in the background, it stops the voice synthesizer from working. It doesn't allow us to access.
There is also the fact that it's very difficult if you don't have proper colour contrast. I know that a lot of parties like to stick to their colours on the website, and that's understandable. However, sometimes that's not the best contrast for someone with low sight.