A network is a group of connected computers that share resources. It can be small, like two laptops linked by a cable. Or vast, like the internet itself. Networks let devices communicate, share files, and access the internet. They are the plumbing of the digital world.

Networks come in many sizes. A LAN covers a home or office. A WAN spans cities or countries. A MAN covers a city. A PAN connects devices around one person, like a phone and earbuds. Each type uses different hardware and protocols.

Network topologies

• Star: all devices connect to a central hub
• Bus: all devices share a single backbone
• Ring: devices connect in a loop
• Mesh: devices connect to multiple others
• Hybrid: combinations of the above

Networks need addresses, protocols, and security. IP addresses identify devices. TCP/IP governs communication. Firewalls and encryption protect data. When a network goes down, everything that depends on it stops. The network is invisible until it fails.