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A computer is a machine that manipulates data according to a set of instructions.
Although mechanical examples of computers have existed through much of recorded human history, the first electronic computers were developed in the mid-20th century (1940–1945). These were the size of a large room, consuming as much power as several hundred modern personal computers (PCs) Modern computers based on integrated circuits are millions to billions of times more capable than the early machines, and occupy a fraction of the space.[2] Simple computers are small enough to fit into a wristwatch, and can be powered by a watch battery. Personal computers in their various forms are icons of the Information Age and are what most people think of as "computers". The embedded computers found in many devices from MP3 players to fighter aircraft and from toys to industrial robots are however the most numerous.
The ability to store and execute lists of instructions called programs makes computers extremely versatile, distinguishing them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: any computer with a certain minimum capability is, in principle, capable of performing the same tasks that any other computer can perform. Therefore computers ranging from a mobile phone to a supercomputer are all able to perform the same computational tasks, given enough time
The Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite (TCP/IP) to serve billions of users worldwide. It is a network of networks that consists of millions of private and public, academic, business, and government networks of local to global scope that are linked by a broad array of electronic and optical networking technologies. The Internet carries a vast array of information resources and services, most notably the inter-linked hypertext documents of the World Wide Web (WWW) and the infrastructure to support electronic mail.
Most traditional communications media, such as telephone and television services, are reshaped or redefined using the technologies of the Internet, giving rise to services such as Voice over Internet Protocol (VoIP) and IPTV. Newspaper publishing has been reshaped into Web sites, blogging, and web feeds. The Internet has enabled or accelerated the creation of new forms of human interactions through instant messaging, Internet forums, and social networking sites.
The origins of the Internet reach back to the 1960s when the United States funded research projects of its military agencies to build robust, fault-tolerant and distributed computer networks. This research and a period of civilian funding of a new U.S. backbone by the National Science Foundation spawned worldwide participation in the development of new networking technologies and led to the commercialization of an international network in the mid 1990s, and resulted in the following popularization of countless applications in virtually every aspect of modern human life. As of 2009, an estimated quarter of Earth's population uses the services of the Internet.
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What is the internet :
The Internet, in simplest terms, is the large group of millions of computers around the world that are all connected to one another. These computers are connected by phone lines, fiber optic lines, coaxial cable, satellites, and wireless connections.
When you log on to the Internet you are given access to many of the other computers that are connected around the world.
Some common ways of connecting to the Internet include:
- Internet service provider (ISP) by modem
- Internet ready cable
- digital subscriber line (DSL)
- simply turning on your computer which is on a network at work or school connected to the Internet
Today you can even get a wireless connection to the Internet with a handheld PC or notebook computer.
Once you are connected to the Internet you are able to do many things. You can send and receive e-mail. You can chat with text or voice. You can browse the World Wide Web. And you can perform countless other tasks with the appropriate software.
The Internet works a lot like a postal or parcel delivery system, except it is much, much faster. Say, for example, you are in California and want to send an e-mail to a friend in London. After you press the send button, your e-mail goes to your mail server. (Your mail server isn't usually part of your computer, but rather part of your internet service provider's computer network, so you can disconnect as soon as you press the send button and it won't interrupt delivery.) The mail server will attempt to contact your friend's mail server in London. But chances are your mail server doesn't have a direct line connecting it to your friend's mail server in London. Your mail server may have to "talk" to a computer in Chicago, which then takes to a computer in Washington, D.C., which contacts the London server via satellite. Or the Washington, D.C. computer might contact London via an undersea cable.
If the satellite or undersea cable appeared to be busy with other Internet data, your mail server may try sending west through Australia or Japan. In theory, the e-mail, although probably just a few paragraphs may possibly be broken into two or more parts and half of it would be sent east and half west. All the pieces would be reconstructed in London in one piece for your friend to read next time they log on.
The Internet is very dynamic. Routers and other computer server hardware try to find the best lines between servers so you get the best possible service. All of these connections are transparent to you, the Internet User. All of these connections look just like a direct connection to you. It makes using the Internet a lot easier.
CAUTION: It is important that you use a secure server when transferring personal information like credit card numbers over the Internet because any stop along the way (again, in theory) could log your credit card number. When you use a secure server, the number is encrypted (coded) and looks like gibberish to every computer except the one you are sending the number to. Look for a "secure server" option before entering your credit card number online.
What is the World Wide Web?
The World Wide Web is what you are using right now (unless you printed out the guide, then you're probably reading a piece of paper). The World Wide Web is the name given to the entire part of the Internet you can access with your web browser software. (Netscape Navigator and Microsoft Internet Explorer are the two most popular web browsers.) The World Wide Web, or WWW or web for short, consists of millions of web sites (like yahoo.com, microsoft.com, and davesite.com) and millions of web pages.
A web page is what you are viewing right now. It's kind of like a word-processing document, except it can contain pictures, sounds, and even movies along with text. Anyone who knows a little HTML (hyper-text markup ********) or has a program capable of saving in HTML can make a web page. (For a free course in HTML, you can visit HTML: An Interactive Tutorial for Beginners, which is one of my other sites.)
The main difference between a web page (or 'home page') and a web site is that a web site generally contains multiple web pages, all linked to one another in some fashion. Some people use the term web page and web site interchangeably but those with Internet experience know the difference.
One of the beauties of the World Wide Web is the ability to hyperlink. (A hyperlink is one of those cool little [usually] blue and [usually] underlined pieces of text that you can click on to go to a different web page.) When someone makes a web page they can place a link on it to virtually anywhere they wish on the web. When someone visits their web page they can just click the link and the visitor's computer automatically loads the linked site in the web browser ******** Most people use links to help their sites' visitors find other useful sites. When someone makes a page about himself or herself just for fun they'll usually add links to pages created by their friends.
Links can connect different web sites on different servers. You can even make a link to this guide if you really wanted to!
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- To:
- Subject:
- Body: (sometimes the body doesn't actually say body, it's just the big area where you type your actual message.)
In the To: field you type the complete e-mail address of the person who will receive the e-mail. You can type anything you want as the subject and body, although the length of the subject is limited. You usually want to keep the subject to just a few words describing the ******* of the body of the e-mail message.
You may also see options for attachments and forwards. You can add files to your e-mail by using the attachment option. You can forward (make a copy) of a message you receive from someone (if you have their permission if necessary) and mail it to someone else with the forward option.
You may also see fields for CC: and BCC: close to your To: field. CC stands for carbon copy. If you want to send a message to multiple people, add the extra people in the CC: field (usually you separate their e-mail addresses by commas). BCC stands for blind carbon copy. BCC works just like a carbon copy, except the e-mail addresses you type in BCC do not show up to the other recipients. (Example: You send a message To: Mary and BCC: Joey. Joey will see Mary's e-mail address, but Mary won't see Joey's e-mail address because you "blinded" it by putting it in the BCC field.)
There are two things about file attachments you need to be careful of. The first thing is that you need to limit the size of files you are sending. An attachment the size of a floppy disk (1.44MB) can take anywhere from a few seconds to a few hours for someone to receive, depending on the speed of their Internet connection. Get permission before sending large files to someone.
The second reason you need to be careful with attachments is because they are one of the most common ways for computer viruses to spread. As a rule you should never open an attachment from someone you don't know or don't trust. And even if you know the sender, don't open an attachment you are not expecting or an attachment that looks suspicious. Some viruses can destroy all the data on your computer so it's best to play it safe.
CAUTION: You can also get viruses by downloading executable files (usually .com and .exe on Windows computers) from web sites. While only a very small percentage of executable files contain viruses you still may get one. Don't download or run executable files from web sites you don't trust.
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