Modem vs. Router: What’s the Difference?

If you’ve ever browsed on the Internet or used it for any purpose, you’ve had to use a modem or a router. These two terms are closely linked and, as a result, they’re often confused or thought of as interchangeable. However, while they do work in tandem, modems and routers are separate devices with different purposes. In this article, we'll discuss how you can use a modem vs. a router and why it's important to understand the difference.

What is a modem?

A modem is a device that provides you with Internet access by connecting to the Internet service provider (ISP). The device establishes and maintains a dedicated connection with the provider to provide a local network. Essentially, a modem is a gateway to the Internet, and you will need a modem if you want Internet inside your home, office, or business.

The term "modem" is short for "modulator-demodulator." The device receives signals from your ISP through the telephone wire, cable lines, or fiber-optic cable. However, all these signals are analog signals. You need a modem because your computer and your Internet take two different signals; the computer accepts digital signals, and the Internet reads analog signals.

Your Internet-enabled devices, such as PCs, laptops, and smartphones, can only read digital signals. A modem translates the incoming analog signals into standard form so that your devices can understand.

A modem also does the same sequence in reverse. It transforms digital signals from your device into analog signals that can be transmitted and read by your computer.

In short, a modem's primary responsibility is to demodulate incoming analog signals into digital signals so that your device can receive them over the Internet. It modulates outgoing digital signals from the device into analog signals out on the Internet.

Modern modems have three ports: one which connects to a power source, one to the router's WAN port, and one to the Internet.

Types of modems

There are various types of modems based on the mode of installation and data transmission.

Internal modems are installed inside computers or devices. They are integrated into a PC's motherboard or expansion card. Because of their slow bandwidth, these modems are used for dedicated computers in small spaces.

External modems typically sit outside the computer system and are connected to the computer using a serial cable. Although these modems are more expensive, they perform well by offering high-speed data transmission rates for offices.

Dial-up modems are analog modems that enable communication between a computer and an ISP via standard telephone lines. With the rise of cable, fiber, and DSL, a dial-up modem is less often used.

Cable modems connect your home or office to your cable Internet provider through coaxial cables. They convert analog data signals into machine-readable formats and vice versa over cable lines, providing excellent speeds.

DSL modems connect computers to digital subscriber line (DSL) networks in order to bring high-speed Internet to homes or businesses. This type of modem uses existing telephone lines to deliver Internet, but most ISPs will send you a modem.

Fiber-optic modems are also called mobile broadband modems. They provide Internet access to computers or local area networks (LANs) without a need for cables. They're ideal for those who want to access the Internet from anywhere conveniently.

Half-duplex modems allow data transmission in only one direction at a time. It either sends or receives data over a communication line, though it can't do both at once. Half-duplex models are primarily used in older communication systems.

Full-duplex modems allow data to be sent and received simultaneously. The modem transmits data signals from both ends at the same time with the goal of enhancing transmission speeds and efficiency.

What is a router?

A router is a networking device that distributes your Internet connections from a modem to your network devices.

It allows available devices, whether they be wired or wireless, to access the Internet through the same connection. With a router, you can connect to the Internet from your desktop computer, laptop, tablet, smartphone, smart TV, gaming console, or any other smart device that you use.

Typical at-home routers have a built-in switch with multiple ports. Your modem connects to the WAN (wide area network) port on the router via an Ethernet cable, and then, all Internet-enabled devices connect to the router's remaining Ethernet ports.

You don't have to wire all your devices to a router, however; a router also broadcasts a WiFi signal so that you can connect multiple wireless devices at once. It allows anyone within range of your WiFi network to access the web from your router's network.

In most cases, your router is also responsible for assigning each of these connected devices a unique IP address via DHCP. These private IPs allow devices on the same network to communicate directly.

A modem and router share connectivity with devices

Types of routers

Just like modems, there are several different kinds of routers that are worth knowing about.

Wireless routers are the most common in homes or office as they require no cables to connect with other devices. They offer stable connections and secure access, as only authorized users can enter the network using a password.

Wired routers require a cable or wire to connect to other devices. These routers are more reliable than wireless routers because of the stable connection, which also provides faster speeds. Wired routers also allow mobile phones to connect via VoIP technology.

Core routers are high-performance routers used as part of the base structure of a network. By design, they allow heavy transfer of data within a network, but not between two networks. They can be either wired or wireless. However, their advanced features - including large memory, high-speed routing, and protocol support - make them more expensive.

Edge routers transmit data packets between multiple networks rather than within a network. These routers are responsible for network address translation (NAT), routing, and security functions, allowing internal devices to communicate with external networks.

What is the difference between a modem and a router? Comparing modems vs. routers

In short, the gist of a modem vs. a router is this: a modem brings Internet to your home, while a router brings Internet to your devices. Compare the differences in the chart below:

Parameters Modem Router
Function Modulates or demodulates signals, going from analog signals to digital signals and vice versa Forwards data packets between computer networks
Internet connectivity Brings Internet from the ISP to your home Distributes Internet to wired and wireless devices, bringing Internet to devices
Connection placement Connects your home networks to the ISP Sits between your modem and Internet-connected devices, like computers
Area network coverage Uses wide area networks to connect to the Internet Creates a local area network to deliver Internet connections to your devices
OSI layer of operation Operates on the data link layer of the OSI model Operates on the physical layer, data link layer, and network layer of OSI model
Number of ports 2 or 3 ports Multiple ports
Is it necessary? Yes, a modem is necessary for your network to access the Internet Not necessary, as you can connect a device to your modem directly without needing a router; however, necessary to connect more than one device at once or connect devices to each other

Though there are many differences between routers and modems, they do share some features. Their key similarities are:

  • Their end goal. Both work to provide Internet access to electronic devices.
  • Their use of data packets. Both transmit data across networking devices via data packets.
  • Their appearances. Routers and modems may look identical, especially if they're from the same manufacturer.

Some ISPs also offer modem-router combination units, sometimes called "gateways." A gateway is an all-in-one device that combines the abilities of modems and routers into one; essentially, it's a modem with a built-in router.

When should I use a modem vs. a router?

If you’re trying to connect to the Internet, chances are, for the same reasons explained above, you will want to use both a modem and a router. They together provide the best service with the fastest speeds and the least limitations for your home network.

You won’t find yourself in a situation where using only a router works best.  Routers are incapable of connecting to the Internet without modems. However, it should be noted that there are a limited set of tasks that wireless routers can do independently. The router assigns an IP address to each device and provides a connection between them.

So, if you’re looking to just send files between individual devices on the same computer network, a router will suffice. But often, it’s better to have an Internet connection, which is where the modem comes in. If you only want to connect a single device to the Internet, it’s possible to use a modem.

Frequently asked questions

Do I need a router if I have a modem? Do I need a modem if I have a router?

Modems are limited without routers, as they won’t be able to separate the WiFi signal for distribution. However, routers are essentially useless without modems.

The modem connects to the router via the wide area network (WAN) port, and then, other devices connect to the rest of the ports wirelessly. This is what allows you to have your phone, your laptop, your Smart TV, and your Google Home all connected and working properly at the same time.

Without a router, you’d only be able to use one at a time. You'd also have to hardwire it to the modem with an Ethernet cable. Modems and routers work together to let you access the Internet with multiple devices and with fast Internet speeds.

How many devices can be connected to a modem?

The number of devices varies depending on the WiFi's capacity, Internet speed, and the devices' bandwidth.

A typical 2.4 Ghz bandwidth device, for example, can comfortably support up to 11 connections without impacting the Internet's performance.

However, keep in mind that overloading a modem affects its connectivity and performance, leading to latency, slow loading, and buffering.

Should I rent or buy a modem or router?

Typically, you can rent both from your Internet service provider and pay a monthly fee. However, many also allow you to pay upfront for a personal router. You can also purchase a router independently. Ultimately, monthly renting fees are more expensive than the initial cost of getting a personal router, but that option is convenient for those who don't know much about modems or routers.

There's no wrong choice; renting is more convenient, but buying gives you more control over what you want in a device.

When do I need a router?

You should get a router:

  • If you intent to connect multiple devices using a single connection
  • When you want to transmit sensitive data securely, as routers provide WiFI encryption and a firewall
  • When you want to transfer files to other devices, like printers or desktops, offline through LANs
  • If you need to manage traffic within your connections

Routers are extremely useful in the networking world for the above purposes.