Computer networks

Why networks exist#

A computer network connects devices so they can exchange data and share services such as internet access, storage, or printing. A local area network covers a limited place such as a home, school, or office. Wider networks connect locations over larger distances.

Switches, routers, and access points#

A switch commonly connects devices inside a local network and forwards traffic toward the appropriate local destination. A router connects different networks and chooses where packets should go next. A wireless access point allows compatible devices to join through radio signals.

Many home devices combine routing, switching, wireless access, and other functions in one unit.

Packets and addresses#

Network data is divided into packets. Packets carry addressing and control information so network devices can forward them and the receiver can reconstruct the data.

Different layers use different kinds of addressing. The important beginner idea is that local delivery and delivery across networks require coordinated identifiers and rules.

Wired and wireless links#

Wired Ethernet is often stable and resistant to radio interference. Wireless networking is convenient and mobile but can be affected by distance, obstacles, congestion, and interference. A strong signal does not necessarily mean the internet connection beyond the local network is fast.

Common mistakes#

The internet is not the same as Wi-Fi. Wi-Fi is one way to connect locally; a device can join Wi-Fi even when the router has no working internet link.

Troubleshooting model#

Check the device, its local link, the local network equipment, the upstream connection, and the remote service in order. This separates a local problem from a wider outage.