I'm glad you asked. This is one of the most common questions that we receive from folks who are new to web accessibility.
A "screen reader" is the generic term for a program that helps blind people use a computer. Simply put, a screen reader will "read" (speak) the content of a page to the blind user.
There are over 15 screen readers on the market today. A screen reader program has hundreds of commands that the blind or low vision person can use to find out what the computer screen is showing.
For example: If a person wants to read the menus that are available in the menu bar, the Alt key by itself will move the cursor to the menus and read the name of the menu currently in focus. The blind person can use Enter or the down arrow to pull down that menu and then use Enter to select the option they want.
So are all screen readers the same? If they are not, what screen reader do I keep in mind when building/maintaining my website?
In Web Access clinics, the Web Accessibility team will test most extensively with JAWS for Windows, because it is currently the most widely-used screen reader (as reported by the WebAIM annual survey).
However, the Web Accessibility team occasionally tests with Voiceover for Mac and NVDA for Windows, both of which are growing in popularity. Most of the students at Berkeley have JAWS for Windows, as it has been purchased for them by the Department of Rehabilitation.
That sounds great, Pecan. Should I learn how to use a screen reader?
The Web Accessibility team does not recommend that a site owner or developer try to learn how to use a screen reader - here's why!
Because there are so many different ways to do things with a screen reader, a sighted person will not truly be able to emulate what it is like for a blind person to use a website. A blind person using a screen reader experiences a website linearly, a little bit at a time. If you can see the screen, you will be reacting to spatial cues that are not available to your blind visitors. It is too easy for a sighted person to see what they want to use and just mouse to it and not really understand how difficult it is for a blind person to do the same thing.
Also, if you have incomplete knowledge of the screen reader's commands, you might think something is an accessibility problem when it's just a matter of knowing the right command to use.
And finally, investing all the time it would take to truly learn a screen reader will mean less time to consider other assistive technologies, such as screen magnifiers, speech input, or alternative mice and keyboards.
Instead, site owners and developers should spend their time learning how to create content and build websites that adhere to best practices for universal accessibility. The Web Accessibility team offers services to help you when you need to test your site.