What is the purpose of the firewall on the iMac??
Also does it matter if it is turned on or off? My mom doesn't know if she should turn it on or leave it off...
It's there to stop attempts to break into the computer from elsewhere on the network or Internet. Turn it on unless there's a reason to keep it off.
Definitely would advice you to turn it on. As long as your internet connection still work with it let it on. It's the minimum of protection everyone should run on it's mac.
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