The Internet

Computer Networks   Introduction Until recently, getting a computer was mostly equivalent to getting a machine that would be used to perform office-related assignments and other calculations. This type of computer was commonly referred to as standalone. Nowadays, a computer by itself is not sufficient. It needs a way to communicate with other computers.   Networking Because a computer can never be complete, it can complement itself by using resources that other, also incomplete, computers have. In order for two computers to share what they have, they must establish some type of communication. This is easily done using a cable and an appropriate object (a network card, also called NIC) inserted in each computer. This means that a cable would go from this object of one computer to the same type of object on the other computer (In the illustration below, we are using an object between the computers, this object is called a hub. It is perfectly possible to connect two computers using one cable that goes from one computer to the other but this works only if you have two computers. If you have more than one computer, then you use a type of intermediary object whose job is to "direct traffic". For example, when one computer A requests to use or open a piece of text that is located in a computer B but to print it in a printer that is connected to a computer C, this intermediary object is able to know what computer has the text, what computer has the printer, and what computer needs these two services. For these reasons, most connections use this intermediary object: the hub): Only computers that are connected can share what they have. A computer A that is connected to a computer B can access what computer B has. When two or more computers are connected, the idea is to let them share and exchange what they contain. If the computers are small, like regular desktop computers, they may become overwhelmed and they may not have enough to share. The next step is to have a "bigger" central computer that holds even more things that other small computers would need (the word big here doesn't necessarily mean that this computer is physically big; it implies that this computer can do more things, for example it can perform more and faster calculations, than the other small computers). Such a central computer is called a server, because its job is to serve other computers (these other small computers are then called workstations): Once again, only a computer that is a member of this network can take advantage of what the network has to offer. If a computer is not connected to this network, it cannot access the information (and/or resources) of this network. As information and resources (things to share) became more and more useful and in demand, servers of different companies started establishing types of connections among themselves, of course following some rules. In fact, in some situations, some big computers (servers) were made simply to provide information to other computers, without needing to know who owned these small computers, why these small computers needed this information, or what to do with them. The internet was born.

Internetworking

 

Introduction

The Internet is a group of big computers connected to share the information they hold. Some of these computers belong to the government. Some of these computers belong to schools (mostly universities). Some of these computers belong to big companies (corporations). Some of these computers belong to small companies. And some of these computers belong to individuals (located in the basement of their mother). There are two things that may already come to your mind: This is wonderful, and this can be messy; right on both accounts. The computers that are connected may not have anything at all in common. To make sure that this communication is possible, a few rules (called protocols) were established so that anybody who wants to make his or her information available to other people through the Internet must follow these rules, no matter what he or she does with the server or computer.

Internet Connection

The rules to make a server available on the Internet are so numerous and complicated that people like you and I started having a headache when trying to figure them out. Therefore, another type of computers was created that allows casual users like you and I to get on the internet without knowing, or being interested to know, how these servers communicate. These new intermediate computers are held by companies called service providers (they are the middle man). When you have a computer and want to get on this internet thing, you use an Internet Service Provider (ISP) who will establish the connection for you and will make sure that your computer can get on the Internet. Based on this, the Internet can be illustrated as follows:

Notice that computers like yours or mine must first connect to an ISP, and the ISP would lead us to the Internet.

This lesson assumes that your computer is ready to connect to the Internet. Because there can be many issues involved, we cannot review them here.

To establish a connection with the internet, your ISP must let you know how to proceed.

A Browser

A browser is a computer application that "understands" the languages (called protocols) of the internet. In order to connect to the internet, you must have this program. Most (normally all) ISPs give you a browser or install one on your machine. The most popular browser is called Internet Explorer and is published by Microsoft. It is freely available. If you don't like it (we will not compare browsers here; that's a complete subject that leads to personal preferences, long discussions, personal experience, and etc), you can use another. The second most popular browser is called Netscape (or Netscape Navigator). It is also freely available. If you still don't like it, there are other browsers such as Opera or Mozilla Firefox. (Without having time to compare browsers, we encourage you to try them all. Except for Internet Explorer and Netscape, the other browsers are mostly free but you are encouraged to help them by making a financial contribution. With Opera, if you don't pay anything, you get an advertisement banner...). A browser is a window object made of five main sections: The Title Bar: On top, it displays a title bar. The contents of the title bar depends:   The Main Menu: Under the title bar, a browser displays its main menu:   The Toolbar: Under the main menu, a browser is equipped with small pictures called buttons. Microsoft Internet Explorer usually displays these buttons on their own range (called a toolbar):   Other browsers display their buttons on the left or even the right side. Some other browsers allow you to change the position of theses buttons The Address: Either on the right side of buttons or under them, the browser is equipped with a wide box called the address (or the address bar):   The viewing area: this is where you see the result:

Web Site/Web Page

A web page is an area of text and other fancy visual effects that you see when you get on the internet (actually it is a file but we haven't learned yet what a file is). A web site is a group of web pages that belong to one section of the internet, such as one person, one company, one school, or one government agency, etc (a web site is similar to a folder or directory but we haven't learned what a folder or directory are). When you get on the internet, you actually access one or different web pages from one or different web sites. To access a web page, you must first get to the web site to which the web page belongs and you must know the name of the web page. The combination of a web page and the web site it belongs to is called its address. To get the address of a web page, you have four main options: If you know the web site that published the web page, you must first go to that web site. To do this, after opening the browser, in the address box, you can type the (complete) address of the page If you have already been to that web page before, you may have book marked it. In this case, you can "recall" the web page using the main menu of the browser or a button on the browser If somebody sent you the address, on the document (such as an email) that was sent to you, you may just click the address that was sent to you (called a link) and the browser would automatically open the web page If you are already on the internet and perform a search, the page that allowed you to do the search will present you with the address (called a link) of the page. You can just click it and you would be taken to that web page

Practical Learning: Connecting to the Internet

You must first find out from your ISP, your teacher, or your boss, etc how to establish a connection with the internet. There are two main ways with some variances. If you are working at home and you use a modem, you can first double-click an icon that your ISP made available on your computer. If you are using DSL at home, you are in a classroom or at the office, the connection is usually established already and it is available all day long so that there is no particular step to follow in order to connect to the internet. In this case, you can simply launch your browser and the internet is available. Open your browser Locate the address box that we described earlier Click anywhere in that box Press End Press and hold the Backspace key until the box is completely empty, then release the down arrow key Type http://www.senate.gov and press Enter Notice that this opens the web site of the United States Senate

 

Using the Internet

 

A Link

A link is a word or a sentence that, when clicked, would lead you to a web page or produces an internet-related action. Because a link is meant for the internet, it is usually displayed in a different color although this depends on the person who created the link. There are two main ways you get a link: Somebody may send it to you as a reference or an indication If you are already on the internet, you may see some words or sentences that coincidentally all display in the same color The color of the link is not really what makes it a link. It is the result of what it produces that makes it a link. To distinguish a link from the other text on a document or a web page, when you position your mouse on it, the mouse pointer usually changes into a closed hand with a pointing finger. Here is an example: A link can also be created on a picture. To indicate that a picture holds a link, when you position your mouse on it, the pointing finger cursor appears.

 

Practical Learning: Using Links

Click the content of the address box and delete its text completely In the address, type http://www.netscape.com and press Enter On the left side of the page, position the mouse on any word. When the mouse pointer changes into a pointing finger, click Notice that a new web page opens Check the contents of the address box to notice that it contains a longer string

Internet Search

Although the internet is highly rich with information, that information is not always organized the way you particularly expect. When "browsing", you may find it hard to get to the particular information you are looking for. To provide an alternative, there are some specialized sites that can perform the search for you, with more or less accuracy. These sites are referred to as search engines. Some of the most popular of them are: Google Yahoo Alexa MSN Netscape Alta Vista Search To do a search, first access a search engine site. Each one of them provides you with a convenient box in which you can type the word or sentence to search and press Enter. After a few seconds, the results would be displayed in a list. You can then click each link and check it. If a link doesn't provide the type of information you are looking for, you can click Back (the shortcut to go back on most browsers is Alt + left arrow key) and click the next link in the list. If you still don't find what you are looking for, you can change the word or sentence that you typed and start searching again. You can also try another search engine site. Most of the search engine sites provide more services than searching the web. For example, both Yahoo and MSN provide free email addresses and the ability to check your email messages. Some of them also allow you to look for a job, a relationship. Most of them allow you to shop. Many of them also provide news, etc.

Practical Learning: Searching the Internet

Delete the contents of the address box Type http://www.search.com and press Enter In the wide white box presented to you, type I want to learn Microsoft Access Click Search. Notice that you are presented with various results Scroll down to see the list of links created by the search engine Click one of the links to visit a result Click the Back button to return to Search.com Change the contents of the search box to Microsoft Access Tutorial and press Enter Notice that the results are a little different Click one of the links

Downloading

Downloading is the ability to get something from the internet and put it in your computer. By default, downloading means that you decide when to get that thing. Unfortunately, some things get into your computer while using the internet. Some of these things don't bother your computer; some others do. This is why you should be restrictive with the sites you visit. By default, sites of big corporations, government agencies, and schools are less harmful, almost not harmful because they are more accountable or more responsible. In fact, most responsible or accountable businesses run sites that are not harmful at all (you are extremely unlikely to get a disease, I mean a virus, from the web site of a big corporation or a government agency). Like everything else in life, the internet was abused and is now the source of some bad behaviors. There is no strict list of things you should do or sites you should not visit. So, welcome to this world of the Internet. Because of bad behaviors some people and corporations have witnessed on the internet, if you work for some corporations or government agencies, or if you are accessing the internet using a public or school's computer, you may not be able to just download anything you want, and these decisions are right (if you want to download harmful things, do it at home or using your own computer; create your own bad experience, be your own victim, learn from your own mistakes; don't do it on someone else's computer. This means that, if a school, an agency, a business, or a corporation prevents you from using the Internet any way you want, it is a valid decision they make and you should live with it). Many big corporations offer free and safe things you can download (big corporations are more responsible and accountable; they can't take the risk of having their name dragged to the mud). For example, if you plan to get into programming, you can check offerings from http://www.sun.com, http://www.borland.com, or Dev-C++. I didn't cite Microsoft, not because I hate the company (I don't) but because most of its free offerings I can remember may be installed in your computer already, such as Internet Explorer, Microsoft Works (which is not really free, it is just that if you buy your computer in a store, it may have Microsoft Works already but if you don't have Microsoft Works and you nee it, you would have to purchase it) or the .NET Framework (the .NET Framework is not really free and it is not a program by itself anyway, it is a library whose job is to complete the operating system; fortunately, while doing that, it comes with free programs for programmers, not for casual users).

Practical Learning: Downloading

If you can, one of the things I suggest you download is OpenOffice. To get it, change the content of the address box to http://www.openoffice.org and press Enter (OpenOffice is extremely unlikely to do any harm to your computer) Find a link that displays Download and click it Follow the steps to download and install it. If possible, I also encourage you to make a financial contribution (I don't work for OpenOffice.org or Sun Microsystems; I don't even know who runs OpenOffice.org. I just know that, as a programmer, this kind of free program is extremely hard to develop and while you can get free things, it is not a bad idea to help financially)

Electronic Mail

Electronic mail, simply called email, allows you to send messages that would traditionally require a trip to the post office. With email, you don't need a stamp or somebody to carry it. In order to use email, you must first have an email address. Normally, your ISP should have given you at least one email address. If you are not sure, contact your ISP. If you work for a corporation or a government agency, the management (or the IT department) also makes sure that you have an email address. If you are a student, the administration of your school usually gives you an email address. This shows you that an email address is usually easy to get. Some restrictions may be imposed on you when you get one of the above mentioned email addresses. For example, you may not be able to check your messages from anywhere such as the public library. If you don't like the restrictions that come with such an email address, you can create what is referred to as a universal email address. Although everything has some restrictions, universal email addresses are more flexible. There are various companies or web sites that provide free email addresses that you can use at your convenience and that allow you to access your messages from any computer connected to the internet. Some of these companies are Yahoo, Netscape, Hotmail.

Practical Learning: Using Email

1. If you don't have an email address, delete the contents of the address box and change it to http://mail.yaoo.com
2. Find a link that displays something like Sign Up Now or something like that. Then click it
3. Follow the steps to create an email address
4. Once you have an email address, get familiar with how to send and receive email (because the steps are different, we cannot review all of them)

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