Using Personal Computers

Section 4: The Internet

Part 1: Introduction

	In this section of the course we will be looking at the Internet - what it is and how it can be used. In particular, we will look at the World Wide Web and e-mail. We will also look at some of the practical issues of accessing the Internet using Windows 95.

	The Internet consists of many computers of different types connected together so that they can exchange information. It is continually growing and now consists of many millions of computers

	There are several ways of connecting to the Internet, but currently the most common is to use a modem. A modem is the computer equivalent of a telephone, and plugs into a conventional telephone socket. It allows the computer to "ring up" and communicate with another computer, as long as that computer also has a modem. A modem can be internal (a card mounted inside the computer) or external (a separate box which plugs into a serial port (or com port - see section 1 of the course). Internal ones take up less room and need no extra cables. However, external ones can be moved from computer to computer, and are slightly easier to sort out if there are configuration problems.
The speed of a modem is usually measured in kilobits per second. Most modern modems are referred to as 56k modems because they can communicate at up to 56 kilobits per second (under certain circumstances - sometimes they are much slower). A 28.8k modem is about the slowest that can sensibly be used for full Internet access, although slower ones can be used if you only use them for e-mail. Note that modems are not just used for connecting to the Internet - it is possible to communicate with another computer without using the Internet, just by "calling" it directly (if you have the appropriate software). However, this is getting less common, and most communication between computers is now done via the Internet, because it is more flexible (and usually cheaper!). Whilst modems are currently the most common way of connecting to the Internet, even the fastest ones are too slow for some of the new Internet applications being developed (such as real time video). Conventional modems have now reached the limits of what is possible with that type of technology, and in the next few years newer, faster ways of connecting to the Internet will become available. One method, ISDN, is available now, but it is expensive (in the UK at least) and still does not offer the kind of performance required. Several new methods are under development, but it is too soon to tell which ones will eventually replace modems. For the moment, if you want to get connected, you have to use a modem. It is interesting to note that when you use a modem to access the Internet, your computer is not merely connected to the Internet, it actually becomes part of the Internet for the duration of the time that you are connected. This raises some security issues which will be discussed later on in the course.
	Use of the Internet itself is free (though some services available via the Internet have to be paid for), but you must pay an Internet Service Provider (ISP) to connect you to it. There are many different ISPs, so it's worth shopping around. Charging rates and quality of service vary - at the time of writing, around £10 to £12 per month is typical for a flat rate service, but cheaper ones are available. You should make sure that the ISP you choose offers local telephone call rates, as you have to pay standard telephone charges all the time that you are actually using the Internet. Some ISPs (such as CompuServe and AOL) offer additional services above and beyond Internet access. However, these ISPs also charge more, so you must decide whether the extra services are worth the price.
	So how does an ISP connect you to the Internet? The full explanation is quite complex, but the basics are as follows. Each ISP has computers which are permanently connected to the Internet. These computers are also connected to the telephone network via modems. When you wish to connect to the Internet, your computer uses its modem to "phone up" one of the ISP's computers - preferably one close to you to keep the phone charges down. Once your the computer and the ISP's are connected via the telephone network, your computer sends your username and password to the ISPs computer to prove that you are entitled to be connected to the Internet via that particular ISP. If your details check out, the ISP's computer then acts as a kind of "go-between", passing messages from your computer on to the other computers on the Internet, and passing messages from them back to your computer.
	Up to this point we have talked about what the Internet is and how you can get connected to it, but we have not discussed what it can be used for. There are actually many different purposes to which the Internet can be put, but the most common are e-mail and the World Wide Web. In fact, the World Wide Web has become so popular since it's invention (less than 10 years ago!) that many people think that the Web is the Internet. However, as we will discover, it is just one of the services available over the Internet. Having said that, there is an increasing trend to allow other Internet services to be accessed via the Web, so that people can often be using other services without even realising it. Another popular service is something called newsgroups (or Usenet). We will look at it briefly later on in the course.

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