You need BOTH. A modem connects to your ISP, a router shares that connection across devices. Most homes use a combo unit or separate devices.
Factor
Router
Modem
Purpose
Shares internet across devices
Connects to ISP
WiFi
Yes
No
Devices Supported
Multiple (10-50+)
One
Required?
Yes (for multiple devices)
Yes (to get internet)
Router
Distributes internet to multiple devices via WiFi or Ethernet.
✓ Pros
Creates local network
Enables WiFi
Manages device connections
Provides firewall protection
✗ Cons
Cannot connect to internet alone
Requires modem first
Modem
Connects your home to your ISP (like Comcast, AT&T).
✓ Pros
Converts ISP signal to usable internet
Provides public IP address
Direct connection to ISP
✗ Cons
Only connects ONE device
No WiFi capability
No network management
The Verdict
You need BOTH unless you buy a modem/router combo unit. The modem brings internet INTO your home from your ISP. The router then shares that internet across all your devices. Think of it like: modem = front door, router = hallway to each room.
Frequently Asked Questions
Can I use a router without a modem?
No. The router needs internet from somewhere. The modem provides that internet connection from your ISP.
Should I buy separate or combo unit?
Separate gives you flexibility to upgrade each independently. Combo units save space and cost less upfront but harder to upgrade.
Which do I plug into the wall?
The modem plugs into your cable/phone jack. The router plugs into the modem via Ethernet cable.