In most cases, your ISP (Internet Service Provider) will provide you with a modem. This device is capable of providing an internet access point for your house. It has an Ethernet port where you can connect your computer directly or otherwise connect another network device, such as a router.
If you have multiple devices to connect to the internet—or maybe you just want WiFi—you will need a router. This device connects directly to the Ethernet port on your modem. Routers come with multiple Ethernet ports of their own and usually WiFi antennas.
A router is designed to forward data packets between computers and networks. Any information sent to the router is directed through a series of networks until it reaches its target destination.
Let's say I want to send an email, the information is sent from my computer to the router, through the modem, and across the internet until it reaches the email servers I use.
Routers also connect multiple devices to the same network using Ethernet ports and often wirelessly. The router is responsible for getting each device online with a unique IP address (usually a local IP). It acts as a hub, directing internet traffic across the network.
The modem gets its name from what it does—it modulates and demodulates wave signals. When a carrier wave reaches the modem, the modem turns the information into usable data packets. These packets reach our devices to create what we know as an internet connection.
These carrier waves can come through different sources, the most common being DSL and cable connections. When it’s time to send information to the internet, the modem translates the data into whatever kind of signal is needed.
You will always need a modem to connect to the internet. These often provide at least one Ethernet port to connect your computer. Routers are useful for adding additional devices to your network, but they aren't necessary.
There are combination devices that provide the features of both a modem and a router. These devices don't take up as much space and make it easier to isolate issues when troubleshooting.
If you're still not sure, ask yourself:
- Do I need WiFi?
- Do I need to connect more than one device to the internet?
If you answered yes to either of these questions, you need a router or a router/modem combo device.