A lot of people think that a modem and a router are the same things.

But they are not. They are different with two separate roles on a network.

If you want internet inside your home or business, you have to have a modem.  

A modem is what brings the internet into your home or business.  

A modem establishes and maintains a dedicated connection to your internet service provider to give you access to the internet.  

The reason why you have to have a modem is because of the two different types of signals that are used on a computer and on the internet.

A computer only reads digital signals, while signals out on the internet are analog.

As analog data comes in from the internet, the modem demodulates the incoming analog signals into a digital signal so that a computer can understand it.

And a modem also modulates outgoing digital signals from a computer into an analog signal as it goes out on the internet.

And this is where we get the word 'modem'. 

The word modem means modulator-demodulator, which is exactly what a modem does.  

It modulates outgoing data from a computer and demodulates incoming data from the internet.

A router comes in after the modem. 

There are different types of routers: routers that are used in businesses and larger organizations; smaller routers that are used in homes and small businesses.

But they basically do the same thing.  For this article, we're going to focus on the small office/home router that most of us are familiar with.

A router is what routes or passes your internet connection to all of your devices in your home or business.  

It directs it to all of your computers, tablets, and phones so that those devices can access the internet.

A typical small office/home router, like this one here, will have a built-in switch with multiple ports so that you can connect multiple devices using an ethernet cable connection.

And it also functions as a wireless access point so that wireless devices such as tablets and laptops can have internet access.

Technically you don't need a router if you only want one of your devices to access the internet.

You can just plug that device's network cable directly into the modem, and then you'll be able to access the internet.

However, like most homes and businesses you're going to have multiple devices that need access to the internet, and that's where you would need a router.

There are also different types of modems. 

Two of the most common types are cable and DSL modems.

So depending on what type of internet you will use, you need to choose the correct modem.

Cable modems are connected to your home using a coaxial cable.

Cable is typically provided by the same company that provides you with cable television such as Comcast, one of the largest providers in the United States.

And DSL modems are connected using a typical phone line.

DSL is provided by companies such as AT&T, which is the largest provider in the U.S. 

When your internet service provider sends you a modem, or if you were to buy one at the store, the modem might be a modem/router combination.  

It will be a modem with a built-in wireless router in one physical device.

Now if you're wondering how hubs and switches relate to routers and modems, especially if you read my other article where I explained the differences between hubs, switches, and routers, just keep in mind that most routers will have a built-in switch inside of them.

There's no need to have a switch if you already have a router that has a switch built into it.

For example, the router I showed earlier has a four-port integrated switch so that it can connect four Ethernet cables for wired devices.

You may only need to add a switch to this network if you need more wired connections for your devices.

You can connect a switch to your router and then add more connections to the switch.

As the internet is routed into your private network, it first reaches the modem, then it goes from the modem to its router with its integrated switch, and then it's passed to all of your devices.

That’s all, hope you’re clear.