does php buffer output?

Ok heres a simple question I can't seem to find an awnser to. Does php place output into a buffer of N size before it sends it back to client? If this is so, if an error is generated in the script, will the output buffer be destroyed (no data goes back to client) or will it be flushed of current content. Also, what is the max size of that buffer (default), or at what size will the buffer be flushed, and if all of this is possible, could one specify max buffer size, is it in a properties file, or could one specify this page to page. Thanks everyone, Christian Calloway