A protocol that establishes, configures, and tests data link connections used by the PPP Link Control Protocol offers PPP encapsulation different options, including the following:

Authentication - options includes PAP and CHAP
Compression - Data compression increases the throughput on a network link, by reducing the amount of data that must be transmitted.
Error Detection - Quality and Magic numbers are used by PPP to ensure a reliable, loop-free data link.
Multilink - Supported in IOS 11.1 and later, multilink is supported on PPP links between Cisco routers. This splits the load for PPP over two or more parallel circuits and is called a bundle.