Section 3: Internet Protocols & Their Function

Learning how computers connected to the Internet exchange data of all types is useful for understanding how the Internet works. The Internet is essentially an immense network of computers that communicate with each other through the transfer of data. To successfully accomplish these transfers, sets of rules, called protocols, are needed. These often-elaborate sets of formal communication rules are designed to ensure that the transfer of data occurs across networked computers with as little data loss and as few errors as possible.

There are different protocols used at different stages of the data-transfer process. Of the dozens of protocols used, let's take a look at some of the most-common ones you will come across as you operate your Internet business.

HTTP-Hypertext Transfer Protocol

You can think of Hypertext Transfer Protocol (HTTP) as the set of rules that gave life to the World Wide Web. You see HTTP in action wherever you go on the Web; it's the acronym (http://) at the front of the nearly every web address you see.

HTTP governs the exchange of files on the Web. Your web browser uses HTTP to send requests to servers requesting the information they have stored. This is what happens, for example, when you type a web address (also called a URL [universal resource locator]) into your web browser's Address Bar and press Enter. The server then uses HTTP to receive the request and deliver the requested file(s) back to the sender.

In short, HTTP is the mechanism that allows the exchange of data over the World Wide Web to take place.

SSL-Secure Sockets Layer

Secure, encrypted communications over the Internet are handled by the Secure Sockets Layer (SSL) protocol that's used by web browsers and web servers. SSL is the industry standard for e-commerce websites to ensure the safe delivery of customers' sensitive information over the Internet. SSL works as an additional layer of Hypertext Transfer Protocol (HTTP), and a web page secured with SSL displays "https" in the Address Bar of the web browser rather than "http". HTTPS stands for Hypertext Transfer Protocol Secure.

TCP/IP-Transfer Communication Protocol/Internet Protocol

Transfer Communication Protocol (TCP) and Internet Protocol (IP) are two separate protocols, but they work together as the basic communications protocol that forms the basis for the entire Internet. If HTTP can be described as giving life to the World Wide Web, then TCP/IP is what gives life to the entire, all-encompassing Internet, of which the Web is a part.

It's helpful to think of TCP as the caretaker of data as it travels over the Internet. TCP establishes communication between two networked computers, breaks the data into groups called packets, checks to ensure the data's integrity, and fixes any problems it may encounter.

IP takes the data presented by TCP and actually delivers it to the networked computer receiving it. IP also establishes the presence of all computers linked to the Internet. An IP Address is a website's location on the Internet, expressed as a numeric form of four sets of numbers (from 0 to 255) separated by dots in this format: 123.152.278.21. This is a numeric form of a website's domain name. Even if a website's URL has a name (such as www.mywebsite.com), it also has a numeric equivalent expressed in these four sets of numbers.

PPP-Point-to-Point Protocol

The rules for connecting a computer to the Internet using standard dial-up telephone lines are governed by Point-to-Point Protocol (PPP).

SMTP/POP3/IMAP-Simple Mail Transfer Protocol/Post Office Protocol 3/Internet Message Access Protocol

Just like TCP and IP work together to govern communications over the Internet, Simple Mail Transfer Protocol (STMP) and Post Office Protocol 3 (POP3) set the rules for the transfer of electronic mail (e-mail).

SMTP is the protocol used to transfer e-mail messages from server to server. For example, when you send an e-mail message to someone at a different company, the message first goes to your company's server and then to the server of the other company. SMTP governs this server-to-server transfer.

POP3 is the protocol an e-mail client needs to receive this same e-mail message from the server. The e-mail client uses POP3 to communicate with the server and obtain the message.

The POP3 standard is being replaced with the Internet Message Access Protocol (IMAP), which has improved functionality over POP3, including manipulating messages stored on a server-such as viewing a message heading and its sender-without actually downloading them by opening the messages. This feature, for example, is found in the Microsoft Outlook e-mail client.

FTP-File Transfer Protocol

Predating the World Wide Web, File Transfer Protocol (FTP) is still an often-used standard to transfer files over the Internet.

FTP is text-based (as opposed to a graphical user interface found with the Web) and is often used to copy files from an individual computer to a server, which makes it especially useful for transferring files to a host server when creating a website. FTP software is used to accomplish this, and WS_FTP (http://www.ipswitch.com), Fetch (http://www.fetchsoftworks.com) and Cute FTP (http://www.cuteftp.com) are three of the most-popular FTP software titles available.

Files can also be retrieved from an FTP site, which is often a simple listing of files in a directory, although some newer sites have a web page interface. The URL begins with "ftp://" rather than the ubiquitous "http://".

These sites generally are secured by requiring a username and password to be accessed. Many Internet sites have material stored that can be obtained by the public for free by using FTP software to download it. This is referred to as "anonymous FTP," because the files can be obtained by logging in using the word "anonymous" as the username.

FTP sites are especially useful when transferring memory-intensive files too large to be transferred as files attached to e-mail messages.

NNTP-Network News Transfer Protocol

USENET, the text-based special-interest newsgroups that was an early component of the Internet, uses Network News Transfer Protocol (NNTP) to allow users to post and read newsgroup messages. NNTP works with newsreader clients that often come bundled with web browsers.

by Robert H. Fraass on Friday, March 11, 2005