ELI5: Explain Like I'm 5

Modem

A modem is a device that connects computers to the internet. It does this by taking data from your computer and sending it through cables or wireless signals to other modems that are connected to the internet. The other modem then sends the data back to your modem and your computer can then use the data from the internet. Modems are a bit like a translator that lets computers understand the internet and use it.