1. One of the two standards for directly connecting computers to the Internet via dialup telephone connections (the other is SLIP). Unlike the older SLIP protocol, PPP incorporates superior data negotiation, compression, and error correction. However, these features add overhead to data and transmission, and are unnecessary when both the sending and receiving modems offer hardware error correction and on-the-fly data compression. See Serial Linux Internet Protocol (SLIP). From QUECID

2. The most common protocol used to connect home computers to the Internet over regular phone lines. Most well known as a protocol that allows a computer to use a regular telephone line and a modem to make TCP/IPconnections and thus be really and truly on the Internet. From Matisse

3. The standard protocol for connection via a modem to an ISP. The term "point-to-point" is used to contrast this technology with preceding techniques that where based upon "multi-point" communication. For example, the popular Ethernet technology is used to connect many computers together in a single local network. Key point: Sniffing PPP dial-up connections is very hard and is virtually never done. From Hacking-Lexicon

4. This provides fairly high speed direct Internet connectivity using a modem. Unlike earlier modem connection methods (which many people still use) PPP is not limited by the software that exists on the host computer. With PPP, all client software (such as Netscape) runs on the local computer. From Faculty-of-Education