What's the Difference Between a Modem and a Router?

Modem vs router — The modem (left) is responsible for bringing the internet into your home or office and the router (right) distributes it to where you need it to go. Wikimedia Commons (CC BY SA 4.0)

You're happily tinkering away on the internet until something happens and your laptop's like, "Surprise! You're no longer online! " And you're like, "Ah! Something must be wrong with the modem or the router or something! "

But in order for that sweet WiFi to flow unobstructed into and throughout your home, both the modem and the router must be working. Sometimes they can be combined into one box, but even so, it's still two different technologies working inside of a single housing. Here's the difference between them:

What Is a Modem?

The modem is the device that brings the internet into your home by sending and receiving data. You rent a modem from your internet service provider (ISP), but you can also save a little money and buy your own. If you look at your internet bill, you might find you're paying a fee every month to rent your modem, where you can usually buy one for the price of less than a year of your rental.

A modem is a box with two ports — a hole that connects it to the internet, and the hole that connects it to either a computer or a router. A modem's job is to modulate and demodulate electrical signals — it takes digital signals from your computer and changes them into analog signals that can travel through a wire or phone line, and vice versa.

What Is a Router?

A router is a separate machine that takes the information from the modem and allows it to be accessed by many different devices. So, if you just have a modem, you can plug it in to your laptop and the internet can be accessed only by that one computer. But if you have a router, you can create a "home network," with the router acting as the distributor of the internet signal to the various parts of your home, as well as a translator so your wireless devices can read the signals from the modem. The router also acts as a traffic cop, preventing congestion of the internet signal — it's much better at this when there are fewer devices working off a single router.

The size router you need depends largely on the size of your home or business. If your space is really large, you can buy a router with several little satellite routers that can help the signal leapfrog around your house.