What Is a Modem?

What Is a Modem?

Your internet connection depends on a device you might not think about often—the modem.

The modem is a small box in your home office or living room that connects your ISP to every device you own. Without it, streaming your favorite shows, joining video calls, or browsing the web becomes impossible.

Below, we’re discussing why they matter and how to choose the right one for your needs.

What is a modem?

A modem connects your home to the internet by converting signals your devices can understand. Your computers, smartphones, tablets, and smart home gadgets all speak digital language. But internet service providers transmit data through telephone lines or cable networks using analog signals. The modem translates between these two types of communication, enabling your internet connection to work.

Think of your modem as a translator at the border between your home network and the vast internet beyond. Data flows in both directions—when you load a webpage, the modem converts your digital request into analog signals that travel through your ISP’s infrastructure. When the webpage comes back, the modem converts those analog signals back into digital data that your device displays.

What does ‘modem’ stand for?

The word “modem" comes from “modulator-demodulator"—a technical name that describes exactly what the device does. Modulation converts digital signals into analog form for transmission. Demodulation reverses the process, turning incoming analog signals back into digital data. This two-way conversion creates the link between your devices and the World Wide Web.

The home network duo

What is the difference between a modem and a router?

People often confuse modems and routers, but these devices serve distinct purposes in your home network. Understanding the difference will help you troubleshoot connection issues and make smarter purchasing decisions.

A modem provides direct access to the internet through your ISP. It acts as the gateway between your home and the outside world. Without a modem, you can’t connect to the internet at all—period.

A router, on the other hand, takes the internet connection from your modem and distributes it to multiple devices throughout your home. The router creates your local network, allowing your laptop, phone, TV, and gaming console to all access the internet simultaneously. It routes data packets to the correct destination, whether that’s another device on your network or a website on the internet.

Here’s the key distinction: without a router, only one device can connect directly to the modem at any given time. The router multiplies that single connection, sharing it across all your devices via Wi-Fi or Ethernet. Modern routers also include security features, such as firewalls, that protect your network from malicious attacks. Many include parental controls that let you manage what content reaches devices in your home.

Types of modems

Your internet connection type determines which modem you need. The three main categories each work with different infrastructure and deliver varying speeds.

Cable modems

Cable modems connect through the same coaxial cables that bring cable television to your home. This makes them convenient for bundling internet and TV services from the same provider. Cable modems generally deliver high speeds suitable for streaming, gaming, and connecting multiple devices. The downside? Connection speeds can fluctuate during peak hours when your neighbors all hop online at once.

DSL modems

Digital Subscriber Line (DSL) modems use existing telephone lines to deliver internet service. They reach both urban and rural areas where cable infrastructure might not exist, making them widely accessible. DSL modems typically offer slower speeds compared to cable options, but they work well for basic browsing, email, and standard video streaming. If your internet needs stay moderate, DSL provides a cost-effective solution.

Fiber-optic modems

For fast internet, fiber-optic modems reign supreme. These devices use light signals transmitted through dedicated fiber-optic cables, enabling data to travel at remarkable speeds. Fiber-optic connections excel at bandwidth-intensive tasks like ultra-HD streaming, large file transfers, and seamless connectivity across multiple devices. The catch? Fiber-optic service availability remains limited compared to cable and DSL, though providers continue expanding their networks.

VoIP modems

VoIP modems combine standard modem functionality with an integrated analog telephone adapter. This allows you to connect a traditional landline phone directly to your internet connection, eliminating the need for a separate phone adapter. VoIP modems work with either DSL or cable internet, merging voice communication seamlessly with data transfers.

What speeds can you expect?

Modem speed gets measured in bits per second (bps), indicating how much data flows through the connection.

Here’s what different speeds mean for real-world use:

Basic usage: Email and light web browsing work at 56kbps, though pages load slowly and frustration builds quickly.

Moderate usage: Streaming music or standard-definition video requires several hundred kbps to 1 megabit per second (mbps) for smooth playback without buffering.

High performance: HD streaming, online gaming, and video conferencing demand speeds near 100mbps or higher. Multiple users streaming simultaneously need even more bandwidth to avoid quality drops.

Understanding these benchmarks helps you match your modem to your household’s internet habits, ensuring everyone gets the connection speed they need.

What to consider when choosing a modem?

Shopping for a modem or modem-router combo? Keep these factors at the front of your mind:

Speed compatibility: Choose a modem that supports your internet plan’s maximum speed. Look for Gigabit Ethernet capability to future-proof your setup as faster plans become available.

Device compatibility: Verify the modem works with all your devices and operating systems. Consider a WiFi mesh system if you need to cover a large home with a consistent signal strength.

Security features: Advanced security measures, such as firewalls and VPNs, protect against hackers and malicious software. Data encryption keeps your information private, while parental controls let you manage access for younger family members.

LAN ports: Basic modems offer one or two Ethernet ports for wired connections. Higher-end models include four ports, accommodating computers, gaming consoles, smart TVs, and other devices that benefit from stable wired connections.

ISP compatibility: Confirm that your chosen modem is compatible with your internet service provider. Some ISPs maintain approved equipment lists—check before you buy to avoid compatibility headaches.

Set up for success

Setting up your home network

Creating a reliable home WiFi network starts with proper equipment placement and configuration. Follow these steps for optimal performance:

1. Place the modem in a location that allows the router (if separate) to broadcast WiFi throughout your home. Avoid basements, closets, or other enclosed spaces that block signals.
2. Use the provided cables to link your modem to the internet service outlet. Connect your computer directly to the modem with an Ethernet cable during initial setup to ensure a stable connection.
3. Connect the router to the modem using an Ethernet cable. Follow the router’s instructions to create a network name (SSID) and secure password. This wireless network becomes what your devices connect to throughout your home.
4. Large homes or buildings with challenging layouts require additional equipment. WiFi extenders boost your existing signal to reach distant rooms. Mesh WiFi systems provide more comprehensive coverage, creating a seamless network across multiple access points. Powerline adapters use your home’s electrical wiring to deliver internet to hard-to-reach spots.

Should you rent or buy a modem?

Many ISPs offer modem rentals, typically charging $10 to $15 monthly. That adds up fast—over two years, you’ll spend $240 to $360 in rental fees. Purchasing your own modem often costs $100 to $200 upfront, pays for itself within the first year, and gives you access to better equipment and faster speeds.

Buying your own modem delivers several advantages beyond cost savings. You control when to upgrade to newer technology. You can choose models with features your ISP’s rental equipment lacks. And you avoid potential privacy concerns—some rental modems allow ISPs to create public WiFi hotspots using your connection.

Looking for an internet provider near you?

The right combination of internet provider, plan, and equipment makes all the difference in your home’s connection. Fast speeds mean nothing if the service doesn’t reach your area, and even the best modem can’t compensate for an inadequate internet plan.

Enter your zip code below to discover which internet service providers operate in your area. Use our comparison tool to compare available plans, speeds, and pricing to find the perfect match for your household’s needs.

Frequently asked questions

Do I need both a modem and a router?

You need a modem to connect to the internet through your ISP. You need a router to share that connection with multiple devices wirelessly or through Ethernet cables. Many people choose modem-router combo units (also called gateways) that combine both functions in a single device, simplifying setup and saving space.

Can I use any modem with my internet provider?

Not all modems work with all ISPs. Cable companies require cable modems, while DSL providers need DSL modems. Even within these categories, providers maintain lists of compatible models. Check with your ISP before purchasing to ensure your chosen modem will work with their service.

How often should I upgrade my modem?

Technology advances quickly, and modem standards evolve to support faster speeds. Consider upgrading every 3 to 5 years, or sooner if you upgrade to a faster internet plan that your current modem can’t fully support.

Sources

[1] Lenovo.com. “What Is a Modem?"

[2] Netgear.com. “What’s a Modem?"