Difference Between a Modem and a Router

Introduction

A common misconception is that a modem and a router are the same, but they are not.
Both have distinct roles in a network.

Function: Brings the internet into your home or business.
Connection: Establishes and maintains a connection to your Internet Service Provider (ISP).
Signal Types: Converts analog signals (from the internet) to digital signals (used by computers) and vice versa.
Terminology:
- 'Modem' stands for modulator-demodulator.
- Modulates outgoing digital signals from a computer to analog signals.
- Demodulates incoming analog signals from the internet to digital signals.

Function: Routes internet connection to multiple devices within your home or business.
Types:
- Business routers.
- Smaller routers for home and small businesses.
Features:
- Built-in switch with multiple ports for Ethernet cable connections.
- Wireless access point for wireless devices like tablets and laptops.
Usage: Not necessary if only one device needs internet access (can connect directly to the modem).

Cable Modem: Connected using coaxial cable.
- Typically provided by cable TV companies (e.g., Comcast).
DSL Modem: Connected using a phone line.
- Provided by phone companies (e.g., AT&T).

Cable Modem + Small Office/Home Office Router: For multiple devices (computers, tablets).
DSL Modem + Small Office/Home Office Router: For multiple devices (computers, laptop, tablet).
Cable Modem + Business Router: For business networks connecting computers and servers.
Single Device: Direct connection to modem without a router.

Integrated Switches: Most routers come with a built-in switch (e.g., 4-port).
Additional Switches: Useful if more wired connections are needed beyond the integrated switch capacity.
Network Flow:
- Internet → Modem → Router with switch → Computers/devices.