Serial Line Internet Protocol (SLIP) is a simple protocol used to connect computers over serial lines, such as telephone lines. It allows for the transmission of Internet Protocol (IP) packets over these connections, enabling devices to communicate with each other. SLIP is lightweight and easy to implement, making it suitable for low-bandwidth applications. However, SLIP has limitations, such as the lack of error detection and support for dynamic IP address assignment. As a result, it has largely been replaced by more advanced protocols like Point-to-Point Protocol (PPP), which offer better features and reliability for Internet connections.