4.1 The Internet

The Internet is a network of networks

The Internet is a global network connecting millions of devices via routers, cables, and communication protocols. It relies on a fault-tolerant design — if one path fails, data can reroute through other paths. No single organization owns or controls the entire Internet, making it decentralized and resilient.

Data travels in packets

Messages sent over the Internet are broken into packets, small chunks of data that travel independently and may take different routes to their destination. Each packet has metadata like sender/receiver addresses. Packets are reassembled in order at the destination, allowing efficient, flexible transmission.

Protocols make it work

Protocols are agreed-upon rules for how data is formatted and transmitted. IP (Internet Protocol) assigns addresses and routes packets; TCP (Transmission Control Protocol) breaks data into packets, ensures reliable delivery, and reassembles them. Together, TCP/IP is the foundational protocol suite of the Internet, enabling scalability and interoperability.

Key terms

Internet

A global, decentralized network of networks connecting billions of devices using standardized protocols.

Packet

A small chunk of data, including metadata, that travels independently across the network and is reassembled at its destination.

Protocol

A set of agreed-upon rules that determine how data is formatted and transmitted between devices.

TCP (Transmission Control Protocol)

Breaks messages into packets, ensures reliable and ordered delivery, and reassembles packets at the destination.

Fault tolerance

The Internet's capacity to keep working correctly even when some parts of the network fail, by rerouting data.

Try an AP-style question

Why is data sent over the Internet broken into packets?

1. They can take different routes
2. They travel faster than light
3. They are always encrypted first
4. They can never get lost in transit