Mobile screen readers
Mobile screen readers are easy to understand and control. They offer a quick and pretty robust way of testing websites on accessibility, revealing many potential accessibility issues. As they are pre-installed on any modern smartphone and do not require a lot of configuration, they are pragmatic testing tools at call - especially for beginners.
There are two major screen readers available on mobile operating systems, both of which are relevant for testing accessibility: VoiceOver/iOS (on iOS) and TalkBack (on Android). The following section assumes that they are configured properly. So if you haven't done this yet, go back and read: