The term TCP/IP stands for Transmission Control Protocol / Internet Protocol, otherwise translated as the communication protocol for communication between computers connected to the Internet.
The standard TCP/IP-a communication protocol- is a package of rules descriptions regarding the communication between computers, how should they be connected to the Internet and how should data be transmitted between them. In this way, this Internet communication protocol defines the rules for computer communication over the Internet. To be more specific, the usage of the TCP/IP protocol is used by the Internet browsers and Internet servers. Thus, when a client starts a request to a server, a TCP connection is established, by default on port 80. An example of the standard of the TCP/IP protocol is the format for the IP address.
Actually, the TCP/IP standard includes a number of other protocols like , covering a large family: TCP (Transmission Control Protocol) for communication between applications, UDP (User Datagram Protocol) for simple communication between applications, IP (Internet Protocol) for communication between computers, ICMP (Internet Control Message Protocol) for errors and statistics, DHCP (Dynamic Host Configuration Protocol) for dynamic addressing, HTTP (Hyper Text Transfer protocol) for communication between browser and a web server , HTTPS (Secure HTTP) for secure communication between a web server and a web browser, SSL (Secure Sockets layer) for encryption of data for secure data transmission, SMTP (Simple Mail Transfer protocol) for the transmission of e-mails, MIME (Multi-purpose Internet Mail Extension) for allowing SMTP transmit multimedia files including voice, audio, and binary data across TCP/IP networks, IMAP (Internet Message Access Protocol) for storing and retrieving e-mails, POP (Post Office Protocol) for downloading e-mails from an e-mail server to a personal computer, FTP (File Transfer protocol) for the transmission of files between computers, NTP (Network Time Protocol) for synchronizing the time (the clock) between computers, SNMP( Simple Network Management Protocol) for the administration of computer networks., LDAP (Lightweight Directory Access protocol) for collecting information about users and e-mail addresses from the Internet, ARP (Address resolution protocol) used by IP to find the hardware address of a computer network card based on the IP address., RARP (Reverse Address resolution protocol) used by IP to find the IP address based on the hardware address of a computer network card, BOOTP (Boot Protocol) for booting (starting) computers from the network and PPTP (for setting up a connection (tunnel) between private networks)
The TCP/IP protocol is based upon the two original protocols TCP and IP working together, where TCP manages the communication between applications (ex: between browser and network) and IP manages the communication between computers. Another characteristic of this protocol is that data transmitted is broken in packets. TCP is responsible for breaking data into IP packets - before sending- and also for assembling them when the packets arrive at the destination. The real one who takes care about the transmission of the packets between sender and receiver is the IP standard.
To emphasize better the role of the TCP/IP for the applications involved in an on-line E-Learning System, the above picture should be explicit.