TCP/IP (Transmission Control Protocol/Internet Protocol)- TCP/IP is a two-layer program. The higher layer, Transmission Control Protocol, manages the assembling of a message or file into smaller packets that are transmitted over the Internet and received by a TCP layer that reassembles the packets into the original message. The lower layer, Internet Protocol, handles the address part of each packet so that it gets to the right destination.
DNS (Domain Name System)- In simple terms, DNS translates host names into IP addresses (and vice versa). This allows us to browse to web sites (among other things) by using text such as http://www.google.com, instead of having to type in the site's IP address (e.g. http://18.104.22.168).
HTTP (HyperText Transfer Protocol)- a protocol (utilizing TCP) to transfer hypertext (A computer-based text retrieval system that enables a user to access particular locations in webpages or other electronic documents by clicking on links within specific webpages or documents.) requests and information between servers and browsers.
FTP (File Transfer Protocol)- A communications protocol governing the transfer of files from one computer to another over a network.
POP (Post Office Protocol)- Protocol that allows single user computers to retrieve electronic mail from a POP server.
SMTP (Simple Mail Transfer Protocol)- A protocol defined in STD 10, RFC 821, used to transfer electronic mail between computers, usually over Ethernet. It is a server to server protocol, so other protocols are used to access the messages. The SMTP dialog usually happens in the background under the control of the message transfer agent, e.g. sendmail but it is possible to interact with an SMTP server using telnet to connect to the normal SMTP port, 25.