The internet protocol, also called IP, is the fundations of the TCP/IP standards. TCP/IP is a public standards that was developed over the past twenty years by research institutions and industries. It allows computers of all sizes, from all different vendors to interconnect to each other. It is an entirely open standard, any vendor can implement the networking function using this standard. The specific implementation varies widely, depends on the hardware and software platforms, depends on the people who wrote the codes. But as long as they follow the TCP/IP standard, their equipment are guaranteed to be able to communication with other TCP/IP compatible nodes.
The entire Internet, whose explosive growth as we see nowadays,
is based in the TCP/IP protocol suite.
The relationship between IP, TCP, which we will cover in the
transport layer) and other protocols are
summarized in Figure 
. Note that IP is
sandwiched between transport layer and link layer. We
will address other layer functions later.
