How does the internet work?
The short answer
The internet works by packet switching. Your data is cut into small numbered packets, each addressed to its destination. Routers read the address and forward each packet one hop closer, choosing another working link if one fails, and the receiving device puts the packets back in order and asks again for any that went missing.
Chapters and transcript
- 0:00
A page becomes numbered packets
A photo or page is cut into small packets of up to about 1,500 bytes. Each carries a header with the address it is heading for and its number in the sequence.
- 0:08
Routers pass them on, hop by hop
Each router reads a packet’s destination, looks it up in its routing table and forwards it one hop closer. No single router knows the whole route.
- 0:17
A broken link? They go around it
If a link fails, routers simply send packets along another working path. There is no switchboard in charge, so pieces of one page can arrive by different routes.
- 0:26
Your device puts them back in order
Packets arrive out of order, so your device sorts them by number. If one is missing, it asks the server to send it again, then rebuilds the page.