Filter Internet NAT Redirection



My Cisco router has an option to:
Filter Internet NAT Redirection

The router help says only:
"This feature uses Port Forwarding to prevent access to local servers
from your local networked computers."

Can you explain to me if we should have this option turned on?
It is turned off by default.

Is this option designed to prevent me from connecting to my own
computers - or is this option designed to prevent outsiders from
connecting to my computers (perhaps via a compromised system)???

Nancy
.