Computer Networks Computer networks connect two or more computers. A common network used by many corporations and universities is a LAN, or Local Area Network. A typical LAN connects several computers that are geographically close to one another, often in the same building, and allows them to share resources, such as a printer, a database, or a file system. In a LAN, most user computers are called clients, and one or more computers act as servers. The server controls access to resources on the network and can supply services to the clients, such as answering database requests, storing and serving files, or managing email. The computers on the network can exchange data through physical cables or through a wireless network. The Internet is a network of networks, connecting millions of computers around the world. The Internet evolved from ARPANET, a 1969 U.S. military research project whose goal was to design a method for computers to communicate. Most computers on the Internet are clients, typically requesting resources, such as webpages, through an Internet browser. These resources are provided by web servers, which store webpages and respond to these requests. Every machine on the Internet has a unique ID called its IP address (IP stands for Internet Protocol). Special computers called routers find a path through the Internet from one computer to another using these IP addresses. A computer can have a static IP address, which is dedicated to that machine, or a dynamic IP address, which is assigned to the computer when it connects to the Internet. An IP address is made up of four octets, whose values in decimal notation are between 0 and 255. For instance, 22.214.171.124 could represent such an IP address. In binary notation, this IP address is 111010.11001011.10010111.1100111. In another post, we will learn how to convert a decimal number, such as 103, to its binary equivalent, 1100111. Most people are familiar with URL (Uniform Resource Locator) addresses that look like https://www.bbc.com/news/magazine-28353027. A URL is actually an Internet domain name as well as the path on that domain to a specific web page. In this URL, the domain name is http://www.bbc.com. The page requested is magazine-28353027 which is located in the news folder.
Domain name resolution servers, which implement the Domain Name System (DNS), convert domain names to IP addresses, so that Internet users don’t need to know the IP addresses of websites they want to visit. The World Wide Web Consortium (W3C), an international group developing standards for Internet access, prefers the term Uniform Resource Identifier (URI) rather than URL, because URI covers future Internet addressing schemes.