Q.Identify some other networks in the real world.

Network Definition: A First Look

Think about the last time you called a friend, sent a WhatsApp message, or even just walked into a crowded room. In each case, you were part of a network — a structure of connections. The phone call connects two people; the WhatsApp group connects many; the room connects everyone in it through sight and sound. A network is simply any collection of nodes (the things being connected) and the links (the connections between them).

In everyday life, you already know dozens of networks. Your family is a network of people connected by blood or marriage. Your school is a network of students, teachers, and staff connected by classes and activities. The roads you travel form a network of intersections and highways. Even your own body has a network of blood vessels and nerves. The idea is so natural that you have been using it your whole life without giving it a name.

The Precise Meaning

Formally, a network is defined by two things:

• Nodes (also called vertices): the individual units or points in the system. In a friendship network, each person is a node. In a transport network, each city or bus stop is a node.
• Links (also called edges or connections): the relationships or pathways that join nodes together. A link exists between two nodes if they are directly connected — two friends who know each other, two cities with a direct flight, two computers that can exchange data.

The key insight is that a network is not just a random collection of connections. It has a structure — a pattern of who is connected to whom — and that structure determines how the network behaves. A tightly-knit group of friends behaves differently from a loose chain of acquaintances, even if both have the same number of people.

Why It Matters

Networks are everywhere, and understanding them changes how you see the world. Consider a few examples:

• Social networks (Facebook, Instagram, LinkedIn) are built on the idea that people are nodes and "friendship" or "follow" is a link. The structure of these networks determines how information spreads, how trends go viral, and how influence works.
• Supply chains are networks of companies, factories, warehouses, and stores connected by the flow of goods. A disruption at one node — a factory fire, a port strike — can ripple through the entire network.
• Communication networks (the internet, telephone systems) are networks of devices and transmission lines. The design of these networks determines whether your call drops or your video streams smoothly. …