The IAccessible interface is the heart of Microsoft Active Accessibility. Applications implement this Component Object Model (COM) interface to represent their custom user interface elements, which can include their client area as accessible objects, if necessary. Client applications call IAccessible methods and properties to obtain information about an application's user interface and data.

The documentation for the IAccessible interface uses the standard COM parameter attributes [in], [out], [in/out], and [out, retval] to identify the direction of the flow of information to and from a function and to specify whether the caller or callee is responsible for allocating memory. If you are unfamiliar with these attributes, see Definitions of Parameter Attributes before reading about the IAccessible interface.

As with any COM interface, the system file initguid.h should be included in any source code that requires Active Accessibility.

For more information about the IAccessible interface, see the following topics:


**  Windows NT/2000/XP/Server 2003:** Included in Windows 2000 and later.
**  Windows 95/98/Me:** Included in Windows 98 and later.
**  Redistributable:** Requires Active Accessibility 1.3 RDK on Windows NT 4.0 SP6 and Windows 95.
**  Header:** Declared in Oleacc.h.
**  Library:** Use Oleacc.lib.