The Internet

(excerpt from "The Whole Internet User's Guide and Catalog")

The Internet was born about 20 years ago, trying to connect together a U.S. Defense Department network called the ARPAnet and various other radio and satellite networks. The ARPAnet was an experimental network designed to support military research--in particular, research about how to build networks that could withstand partial outages (like bomb attacks) and still function. (Think about this when I describe how the network works; it may give you some insight into the design of the Internet.) In the ARPAnet model, communication always occurs between a source and a destination computer. The network itself is assumed to be unreliable; any portion of the network could disappear at any moment (pick your favorite catastrophe--these days backhoes cutting cables are more of a threat than bombs). It was designed to require the minimum of information from the computer clients. To send a message on the network, a computer only had to put its data in an envelope, called an Internet Protocol (IP) packet, and "address" the packets correctly. The communicating computers--not the network itself--were also given the responsibility to ensure that the communication was accomplished. The philosophy was that every computer on the network could talk, as a peer, with any other computer.

What is the World Wide Web's place in the Internet?

World Wide Web (WWW or Web) is one facet of the Internet consisting of client and server computers handling multimedia documents. Client computers use browser software (such as Netscape Navigator) to view documents (pages). Server computers use server software (such as

the Netscape Commerce Server) to maintain documents for clients to access.

Web documents are created by authors using a language called HTML (HyperText Markup Language) that offers short codes (also called tags) to designate graphical elements and links. Clicking on links brings documents located on a server to a browser, irrespective of the server's geographic location. Documents may contain text, images, sounds, movies, or a combination.

Documents are addressed with a URL (Uniform Resource Locator or, for short, location). Clients and servers use a document's URL to find and distinguish among documents.

How can I access the Internet?

Some companies maintain a network that is linked to the Internet via dedicated communication lines. Those with less substantial resources, including most individuals, access the Internet via a service provider. A service provider is a company that offers use of its dedicated communication lines. If you have a modem, you can dial up a service provider whose computers will connect you to the Internet, typically for a fee. Dial-up access means that the modem on your computer can log in to another computer that is hooked up to the Internet. The most popular dial-up access alternatives are shell accounts and SLIP/PPP accounts. When using a shell account, you dial into a service provider's computer and use the UNIX operating system to indirectly connect to the Internet. With an indirect connection, your computer does not interact with Internet computers. For example, if you download a file from an Internet site, the file is saved on the service provider's computer rather than on your computer. You then have to transfer the file from the service provider's computer to your home system. Shell accounts, while limited in features, have historically been less expensive than direct access accounts.

When using a SLIP or PPP account, you dial into a service provider's computer and run applications that directly connect to the Internet. With a direct connection, your computer can use browsers with user-friendly graphical interfaces to interact with Internet computers. A direct connection lets you download files directly to your system from remote sites. SLIP or PPP access to the Internet offers more performance and convenience than a shell account.

What are SLIP and PPP?

SLIP, short for Serial Line Internet Protocol, and PPP, short for Point-to-Point Protocol, are Internet standards for transmitting Internet Protocol (IP) packets over serial lines (phone lines). Internet information is packaged into IP packets, a method for enclosing data into small,

transmittable units (wrapped up on one end, unbundled on the other).

A service provider may offer SLIP, PPP, or both. Your computer must use connection software (usually provided by the service provider) that matches the protocol of the server's connection software. PPP is a more recent and robust protocol than SLIP.

TCP/IP

TCP/IP, short for Transmission Control Protocol/Internet Protocol, is the standard communications protocol required for Internet computers. To communicate using TCP/IP, PCs need a set of software components called a TCP/IP stack. Macintoshes typically use a proprietary software called MacTCP. Most UNIX systems are built with TCP/IP capabilities.

Netscape Navigator

The greatest concentration of ex-NCSA Mosaic developers can be found at the Mountain View offices of startup Netscape Communications.

Founded by Jim Clark, previously head of Silicon Graphics, and Marc Andreessen, who created the first NCSA Mosaic, Netscape has gone

from complete obscurity to being one of the heavy hitters in the world of the Web. The reason? Netscape Navigator, which is what happens

when you take talented developers and ask them to write a program they've done once all over again from scratch, avoiding the mistakes they

made the first time and rethinking the parts that didn't work well. Netscape Navigator basically owns the Web browser market, if you can call it that since most Web browsers are essentially free, with some estimates giving it as much as 75 percent market share.

Netscape Navigator (generally just called Netscape, thanks to some weaseling around with the name early on, when the company was called

Mosaic Communications and the program was called Mosaic Netscape) shines in two specific areas. It's fast, thanks to an innovative way of

establishing multiple connections to the server when you retrieve a Web page, and it has, by far, the best hotlist feature (called bookmarks in

Netscape's parlance).

Note: HTML, or HyperText Markup Language, is the language in which documents are written for display on the Web. Actually, there's a third major reason Netscape took the Web by storm. Netscape Communications "extended" the standard HTML 2.0 tags in advance of the forthcoming HTML 3.0 specification, and supported those extensions in Netscape. The result is that people writing in HTML can do things graphically, such as wrap text next to a graphic, that were previously impossible (and still are in other Web browsers). Suddenly, if you wanted to see a page in all its glory, you had to use Netscape. Many people felt that Netscape's jumping of the gun wasn't particularly fair play, and many Web page developers refuse to use Netscape-specific HTML codes until the HTML 3.0 specification is complete (which should be relatively soon -- sometime in mid-1995 is my guess). At that point MacWeb and Mosaic will almost certainly add support for all the additional HTML codes that enable Web page developers to create tables, wrap text around graphics, place graphics in specific spots on the page, and so on.

A Few FAQ Sites on the Web

http://www.spp.umich.edu/telecom/technical-info.html

http://www.surf-ici.com/faqdocs.htm

http://sunsite.unc.edu/boutell/faq/www_faq.html

http://www.netscape.com/eng/mozilla/1.1/handbook/docs/answers.html