Firewall(s)

Iv'e read that Routers have their own Firewalls.So you don't need to install one on your PC. Is this always the case? Or,do some routers not have a firewall?
If your router does have a firewall,is it O.K. to download one on your computer anyway? Or would two of them cause problems?
How do you know if your router does have a firewall ? Thanks for any info CB

The Differences and Features of Hardware and Software Firewalls

Good protection is a hardware firewall (in the router)) plus installing a software firewall to run on each computer. You don't want to have more then one software firewall running on a computer

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Check your router manual to see what firewall functions it provides.

So running a firewall on my computer is a good idea,no matter how you look at it.
If my Router has a firewall,I'm doubly protected.If it doesn't,at least I'm protected by my computer firewall. Thanks CB