The Linux operating system was originally conceived and written by Linux Torvalds with the assistance of many people all over the world. It was intended to be an open source replacement for Unix and is compatible with Unix in almost every respect. The TCP/IP stack is implemented as part of the Linux kernel. It is also compatible with all the applicable Posix standards. Almost all programs written for Unix readily port to Linux without modification. Like the rest of the operating system, the TCP/IP stack was specifically designed for compatibility. In addition, it is completely interoperable with other TCP/IP implementations. It provides a socket interface that is compatible with Berkeley sockets. The code in Linux TCP/IP is very stable, and this is demonstrated by how few changes there are to the TCP/IP code in recent revisions.