TCP/IP in turn consists of two layers.
Each packet receives the IP addresses of both the sender and the target computers before it is sent off, and every computer that receives the packet on the way checks this address to determine which computer it should forward the packet to next. As a result, every packet may be processed by many computers on the globe before it arrives at your computer. Packages from the same original data chunk may take different paths over the network, but will be reassembled correctly by TCP.
Note that when you temporarily connect to your Internet Service Provider (ISP) to get access to the Internet, you will usually do so with the use of an additional protocol, the Point-to-Point Protocol (PPP). This encapsulates the IP packets so that they can be sent over a dial-up phone connection to an access provider's modem.
Internet services such
as the World Wide Web (WWW) and e-mail are also implemented as additional
protocol layers on top of TCP/IP. Those layers however are not integrated
into the operating system's networking components, but rather provided by
the individual Internet applications such as your Web browser. These
protocols include the Hypertext Transfer Protocol (HTTP) used by the WWW,
the File Transfer Protocol (FTP), Telnet (Telnet), and the
Simple Mail Transfer Protocol (SMTP) for mail.