PPP - Point to Point Protocol is a Form of serial line data encapsulation that is an improvement over SLIP which provides serial bi-directional communication. it is mush like SLIP but can support AppleTalk, IPX, TCP/IP, and NetBEUI along with TCP/IP which is support ]ed by SLIP. it can negociate connection parameters such as speed along with the ability to support PAP and CHAP user authentication.