Screen reader support and basic accessibility information

Screen readers provide access to the text in an app by rendering it in some other format, such as spoken language or Braille output. The exact behavior of a screen reader depends on the software and on the user's configuration of it.
For example, some screen readers read the entire app UI when the user starts or switches to the app being viewed, which enables the user to receive all of the available informational content before attempting to navigate it. Some screen readers also read the text associated with an individual control when it receives focus during tab navigation. This enables users to orient themselves as they navigate among the input controls of an application. Narrator is an example of a screen reader that provides both behaviors, depending on user choice.
The most important information that a screen reader or any other assistive technology needs in order to help users understand or navigate an app is an accessible name for the element parts of the app. In many cases, a control or element already has an accessible name that is calculated from other property values that you have otherwise provided. The most common case in which you can use an already-calculated name is with an element that supports and displays inner text. For other elements, you sometimes need to account for other ways to provide an accessible name by following best practices for element structure. And sometimes you need to provide a name that is explicitly intended as the accessible name for app accessibility. For a listing of how many of these calculated values work in common UI elements, and for more info about accessible names in general, see Basic accessibility information.
There are several other automation properties available (including the keyboard properties described in the next section). However, not all screen readers support all automation properties. In general, you should set all appropriate automation properties and test to provide the widest possible support for screen readers.