group11_DNAA: how does internet work

Internet is a world wide system of computer networks in which users at any one computer can get information from any other computer. Each computer connected to internet must have a unique address called as an IP address. The message transfer between the computers is usually over wires. The message must be translated from alphanumeric text into electronic signals, transmitted over internet, then translated back to alphanumeric text. This is accomplished by using a protocol stack which is usually built into computer's OS. The protocol stack has four layers- application protocol layer, transmission control protocol layer, internet protocol layer, hardware layer.
The message would start at the top of the protocol stack on the computer and work its way downward. The message would be sent as chunks of data called packets. Each packet will have a port number. The IP layer would help to know the address of the destination computer. TCP layer helps to know which program on the destination computer needs to receive the message because it will be listening on a specific port. The hardware layer takes care of turning the packets containing the alphanumeric text of the message into electronic signals and thus transmitting it.The ISP router examines the destination address in each packet and determines where to send it. The packets start at the bottom of the destination computer's TCP/IP stack and work upwards. When the data reaches the top of the stack, the packets are reassembled into their original form.
One of the internet's major services is the World Wide Web. Web documents can be linked together because they are created in a format known as hypertext. Hypertext systems provide an easy way to manage large collections of data. To support hypertext documents the web uses a special protocol called Hypertext Transfer Protocol or HTTP. A hypertext document is an encoded file which uses the hypertext mark up language or HTML. This language allows a user to embed hypertext links or hyperlinks in the document. HTTP and hypertext links are the foundation of the World Wide Web.