WHAT IS A SEARCH ENGINE?
With billions of items of information scattered around the World Wide Web how do you find what you are looking for? Someone might tell you the address of an interesting site. You might hear of an address from the TV, radio or a magazine. Without search engines, these would be your only ways of finding things. Search engines use computer programs that spend the whole time trawling through the vast amount of information on the Web. They create huge indexes of all this information. You can go to the Web page of a search engine and type in what you are looking for. The search engine software will look through its indexes and give you a list of Web pages that contain the words you typed.
HOW DOES THE INTERNET WORK?
The Internet is made up of hardware and software. The word hardware describes all the actual machinery. That includes all the computers and all the devices and cables that connect them. The word software describes the programs that run on the computers and the connecting devices. These programs contain instructions that tell the hardware what to do.
The key feature of the Internet is that it allows many different types of computer to talk to each other. Other types of machine such as robots or cameras can also be connected to the Internet. This allows them to be controlled from afar. People have connected all kinds of machines to the Internet, such as drinks machines, model train sets and even fridges.
To allow different types of computer or machine to communicate, scientists devised sets of rules known as protocols. The protocols work almost like languages. As long as the software on one machine uses the same protocol as another, the machines can understand each other. If all the machines on the Internet use the same protocols they can all understand each other.
Every computer connected to the Internet has a unique number. Information moves around the Internet in little chunks called packets. Each packet carries the number of its destination, a bit like an address on an envelope. Computers connected to the Internet pass the packets on from one to another until they reach their final destination. The whole journey takes a split second.
Humans prefer to use names instead of numbers, so there are special machines on the Internet that act like telephone directories. They take the names we type in, such as www.microsoft.com, and convert them into the number of the machine we are trying to contact.