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Class 12 • Chapter 6
Networking connects devices for sharing data and resources, categorized by geographical scale (LAN/WAN) and physical layout (Topologies).
A computer network is a system of interconnected computers and peripheral devices (like printers, scanners, and servers) that can exchange information and share resources. The evolution of networking began with ARPANET in the late 1960s, which eventually grew into the modern Internet. Today, networks are the backbone of global communication, digital economies, and social interaction. By connecting machines, we gain efficiency through resource sharing (like a single high-end printer for an entire office) and reliability through data redundancy. Whether it is a simple Bluetooth connection between a phone and a watch or the massive fiber-optic cables spanning continents, the underlying principles of routing and switching remain fundamental to how digital data travels.
Networks are categorized based on the physical area they cover. **PAN (Personal Area Network)** is for individual use within a few meters (like Bluetooth). **LAN (Local Area Network)** covers a limited area such as a school building or an office, providing high speed and low error rates. **MAN (Metropolitan Area Network)** connects LANs across a city or a large campus. The largest is **WAN (Wide Area Network)**, which spans across countries and continents, such as the Internet itself. Each type uses different technologies: LANs often use Ethernet or Wi-Fi, while WANs rely on satellite links and deep-sea fiber optic cables to bridge massive distances.
Topology refers to the physical or logical arrangement of nodes in a network. **Bus Topology** uses a single 'backbone' cable to connect all nodes, making it cheap but prone to failure if the backbone breaks. **Star Topology** connects all nodes to a central hub or switch; it is the most popular today because a failure in one node does not affect others. **Ring Topology** connects nodes in a circle, where data travels in one direction. **Tree Topology** is a hierarchical arrangement (often used in large organizations), combining features of Bus and Star. Choosing the right topology is a critical engineering decision that impacts the network's cost, scalability, and fault tolerance.
Data is transmitted through physical channels called media. **Guided Media** (Wired) include Twisted Pair cables (used for telephone and LAN), Coaxial cables (used for cable TV), and Optical Fibers (which use light pulses for ultra-high speed over long distances). **Unguided Media** (Wireless) include Radio waves (used in Wi-Fi and Bluetooth), Microwaves (line-of-sight communication), and Infrared (used in remote controls). Optical Fiber is considered the gold standard for modern networking because it is immune to electromagnetic interference and can carry significantly more data than traditional copper wires.