is used to return to the computer a chunk of memory that was previously reserved for your application via the GetMem command.

const
   BufSize=4096;

var
   Buffer:Pointer;

Begin
   GetMem(Buffer, BufSize);
{.. Use the Buffer ..}
   // When finished:
   FreeMem(Buffer, BufSize);
End.

Source: Reserved Words

See Also:

new, getmem, dispose,.