TCP/IP is a two tier module. Transmission Control Protocol, the upper tier, controls the assemblage of a file or message into smaller packs that are then sent out over the network and accepted by a TCP tier that rebuilds the packs into the previous message. Internet Protocol, the lower tier, manages the address element of every pack so that it is delivered to the correct destination. Every access computer on the system verifies this address to check where to send the message. Although, some packs from one message are transmitted differently than the rest, they'll be rebuilt at the destination.
TCP/IP employs the user/server communication model wherein a client (a computer user) requests and is offered a service (like sending a Webpage) by a server (other computer) in the system. Primarily, TCP/IP communication is end-to-end, implying each message is from a host computer (one end) in the system to another end or host computer. Higher-level applications and TCP/IP that employ it are jointly called to be "stateless" as each user request is measured as a fresh request not related to any earlier one (not like normal phone talk that need a continued connection for the duration of the call). Being stateless liberates network routes so that anyone can use them continually.