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One area that frequently confuses people about the Internet is the fact that it is possible to Interact with the Internet on many different levels. Each of these different levels of connectivity implies different compromises between speed, expense, and capability. The connection we are concerned with here is the personal computer or LAN to the router. there are also differing ways of connecting the router to the Internet beyond, but that is beyond the scope of this course.
The most powerful type of connection is a direct connection. A computer with a direct connection is always attached to the router, usually with some type of high-speed phone line or fiber - optic cable. A direct connection is VERY expensive, but it is powerful and fast. Most computers that work as servers have some kind of direct connection, but such a connection is often too expensive for a typical user who is not interested in SERVING information as much as being a CLIENT.
There are a number of compromises we can make so that a computer that does not have a direct connection can still have some type of relationship with the Internet. Many companies and most universities have one or more mainframes or other large computers with direct connections to the Internet. Members of that organization are give accounts on those huge machines, with a small amount of hard drive space dedicated to that individual. These large computers are also frequently attached to a bank of modems. People with modem - equipped computers at home and accounts on these large computers can use special software to have their home computer call the larger machine. Once the communication is established, the home computer becomes a terminal to the large one. Note that this is functionally very similar to telnet. The only difference is in the type of connection. Telnet is between two computers which BOTH have IP numbers and connections to the Internet. In a dial - in connection, only the large computer has an IP number, and the home computer does not exist as far as the Internet is concerned. All transactions happen in the CPU and drive space of the LARGE computer. The home computer is nothing more than a terminal. If you used such a connection to download a specific piece of software, for example, that software would be stored in your drive space on the LARGE computer. You would need to use other strategies to copy it from that large computer to your computer at home. Obviously, this is a bit of a disadvantage. Another disadvantage of this type of connection is that a dial in connection usually implies only command - line interfaces, which are a bit ugly and difficult to work with. No matter how nice the graphics and sound capabilities of your home computer might be, they are tied to your own CPU and will not be utilized when you are using a dial - in style connection. Still, dial in connections are very popular because they are extremely inexpensive to maintain, provide the most important Internet services, and work with even very limited home computers. Most universities give all students at least limited dial - in service.
Another approach is becoming more popular, because it offers many of the benefits of direct connection, but can still be done at a home without a permanent dedicated Internet phone line. This approach is called PPP (Point to Point Protocol). A related protocol is called SLIP (Serial Line Interface Protocol). PPP is replacing SLIP. For our purposes, we will consider them the same thing. An organization with PPP capability may be set up the same way as the dial in service model. There is a large computer with a permanent direct connection, and a number of people with smaller home computers that want to connect to the larger machine through cables or phone lines. When these machines are connected via PPP, the larger machine has its own IP number, and a bank of temporary IP numbers it is allowed to "check out," like library books. Your home computer must have a special program that knows how to hook up to the large computer and "check out" an IP number. You activate this software, and it makes the connection to the large computer through your modem. As long as this connection is open, your computer has its own albeit temporary IP number. In effect, you have 'faked out' the Internet into believing you have a direct connection.
With a PPP connection, it is really your computer at home with the Internet connection. You can run programs that take advantages of your graphics and sound capabilities (like most web browser programs), and anything that you save will be saved to your own computer, not the large one. When you break off the connection, the IP number you borrowed will be returned to the pool. The next time you utilize this service, you may get a different number.
This approach is not terribly expensive to maintain, and it allows people to take advantages of their own computer's capabilities. The user has to set up the PPP program as well as setting up and installing any client software he wants to use. This can be intimidating, but it gives the user a great deal of power.
A PPP connection is not appropriate for server programs or information. For example, if you wanted to make a web page and make it available to everyone on the Internet, you couldn't do it with a PPP account alone.
The most popular way for people to get started on the Internet and related issues is through commercial service providers. If shirts with little alligators were the icon of the '80s, floppy disks in the mailbox promising 10 free hours of Internet access may well be the icon of the 90s. The number and type of such providers has changed dramatically in the last few years, and it is easy to be confused about them.
Before the Internet became popular with the general public (Waaaaaay back in....say, 1990!) there were a number of privately owned corporations which provided services much like the Internet. The most prominent of these are Compuserve, Prodigy, and America Online, although there are many others. These 'private networks' have some significant differences from the Internet at large. They are generally placed on one large computer or network with many many modem ports. The information on the system is privately owned or contracted. Such systems might have extra controls that the Internet does not have, such as 'censoring software' that automatically rejects any messages which contain objectionable words or phrases. (who decides what is objectionable?) The materials on such networks can be much more clearly defined and organized, because they are not created as randomly as the Internet at large. Originally, each of these services was an independent 'information island.' If you belonged to one service and your sister to another, you were pretty much out of luck. These days, the proprietary networks all have some kind of link to the Internet, and allow you to exchange email and web pages with anyone in the world who has any kind of Internet access. The down side is the cost. Once your free hours are over, you pay the service by the hour. There are many stories of people racking up horrible on-line bills by losing track of the time. This is especially troublesome if you spend all this time using the service provider as a gateway to the Internet, because the Internet stuff cost the provider almost nothing! If what you really want is Internet access, and you will want to be online more than a few hours a month, these providers may not be the most cost - effective technique for you.
Internet Service Providers (ISPs) are a new class of business that suddenly came into being within the last few years. These providers are simply folks who own large computers with direct connections and hard drive space for rent. When you sign up with one of these providers, you can get varying levels of service. Most people get some kind of PPP access and drive space for email and other permanent document storage. In this way, you always have an Internet presence online, for a relatively small amount of money. Many of the ISPs offer programming services and business accounts, so you can get a web page for your small business, for example. The ISP approach is probably the best bet if you plan to be connected to the Internet for more than a few hours a month, and want to experiment with other Internet ideas such as building homepages and doing business online.
The problem with ISPs is that the business is so new that there are very few controls. Check around with any of the computer types you know to see which are the most trustworthy ISPs in your area. This field is bound to change as telephone companies and other large corporations get into the fray.