What This Chapter Covers

A single computer working on its own is useful, but a computer that can talk to other computers is far more powerful. The moment two or more computers are joined so that they can share data, programs, and devices, we have a computer network — and the largest network of all, joining hundreds of millions of computers across the whole world, is the Internet. Networking is what makes e-mail, the web, online banking, e-commerce, video calls, and social media possible, and it is now the backbone of almost every business.

This chapter — part of the second-year Information Technology elective in the Odisha CHSE +2 Commerce course — builds a complete picture of networking in three connected parts. The first part looks at computer networking itself: why we build networks and what benefits they give, the different types of network (PAN, LAN, MAN, and WAN), the network devices that join computers together, the physical arrangements (topologies) in which they are wired, and the communication media — wired and wireless — that carry the signals. The second part looks at the Internet and its applications: what the Internet is and how we connect to it through an Internet Service Provider, the protocols and addressing that let computers find and understand one another, the many everyday applications of the Internet, and the wireless and mobile technologies (GSM, CDMA, WLL, and the 3G/4G generations) that keep us connected on the move. The third part looks at network security and open standards: the threats to a networked computer (viruses, worms, and other harmful programs), the ways we protect against them (safe practices, firewalls, and digital signatures), the meaning of cookies, the common cyber crimes and the cyber laws that deal with them, and finally the important idea of open standards and open-source software.

The networking and security ideas taught here are the standard, well-established principles of computing that are followed everywhere; this is a state-specific IT elective built on those same principles, written in our own words, and is not a reproduction of any particular publisher's textbook.

The chapter is organised as follows: computer networks and their benefits (Section a), types of networks (Section b), network devices (Section c), network topologies (Section d), communication media (Section e), the Internet and how we access it (Section f), Internet protocols and addressing (Section g), applications of the Internet (Section h), wireless and mobile communication (Section i), network security — threats and protection (Section j), cyber crimes and cyber laws (Section k), and open standards and open-source software (Section l).