I removed the receptical I was going to get power from and found 2 cables entering the box. One was a 14-2 and the other was a 14-3. Both black wires were connected to the brass screws and both white wires were on the silver screws. The red wire was pushed into the hole in the back next to the hot wires. I was courious on what that was for? The tab is not broken and the outlet is not controlled by any switch. Any ideas why this is wired like this? Thank-you

If the receptacle is not controlled by a switch, the red wire is just carrying a separate "hot" circuit to it's destination. Unusual, but not necessarily wrong.

Run into funny stuff from time to time. The last time I saw this I asked the homeowner why, 14/3 was all he had when he extended the circuit. That red wire may be nothing, test it.

Run into funny stuff from time to time. The last time I saw this I asked the homeowner why, 14/3 was all he had when he extended the circuit. That red wire may be nothing, test it.

My thoughts as well. Although I hate to admit it; I had to do this very thing this past summer when I added another receptacle in my home.

If the Red is pushed into the Back of the receptacle, they may have forgotten to break the tab.
Easy way to tell is if you have a wall switch that does nothing, and testing switch, you will find power at both terminals wheather switch is on or off. If this is the case, remove power, break tab.
Red and black should not both be connected to the same Hot. You cannot Parallel conductors smaller than 1/0 or more than 50 volts.