Short for Serial Line Internet Protocol, a protocol for connection to the Internet via a dial-up connection. Developed in the 80s when modem communications typically were limited to 2400 bps, it was designed for simple communication over serial lines. SLIP can be used on RS-232 serial ports and supports asynchronous links.
A more common protocol is PPP (Point-to-Point Protocol) because it is faster and more reliable and supports functions that SLIP does not, such as error detection, dynamic assignment of IP addresses and data compression.