What does revving yor car do?

My dad has an old 2014 Honda Civic and he just recently got me a new 2016 Honda Civic. Today I saw my dad opening my car's hook and his car's hook. He attached some kind of wire I think to both of the cars and then he went inside my car and revving it. What exactly was he doing?

Sounds like his car needed a jump start as it had a flat battery.,

Giving the other car a few revs for a couple of minutes gets the alternator charging properly, to put some power into the flat battery, and make the jump start easier. Alternator does't make much power at idle, you want the engine running at 2-3,000 revs to start recharging the battery.

Once his battery have "some" charge, then both batteries combined would start his engine, and he can go for a drive to properly recharge his battery.

PS, ask him to teach you how to do this properly. It's useful if you ever get stuck with a dead battery, But dangerous if you don't know what you are doing.

Sounds like one of the batteries was low on its charge or just bad and he was using the "wires" called jumper cables to charge or start the car with the bad battery.

Sounds like he was using your car to jump start his car. Revving your engine increased your car alternator output, which helped recharge his battery a little.

Ask him to show you how to jump start a car. This is a skill that all drivers should have.

Probably he was using the battery of the other car to jump start his car, that is necessary if a cars battery is discharged and not able to supply the starter with enough electricity to start the engine, for that a cable is attached to the to the plus pole of one car and the batterys plus pole of the other car and reving the engine higher is better to make the alternator produce more power to easier jump start the other car without draining the own battery to much.

reving high doesn't damage a cars engine at all, if the cars engine is already warmed up, the rev limited isn't removed and --whats very important-- the cooling is sufficient if reving the engine high for a longer time as high rpm increases heat development. When the hood is open, then the heat can escape much better, if that is sufficient for cooling together with the fan on the radiator, then the engine can rev all day and all night very high and there won't be a damage in the engine, except the engine will wear out a bit more but that will be only very little wear, because jump starting a car as written in the beginning takes only seconds, far to short time to cause any significant wear out, maybe an engineer with a million dollar measure equipment would be able to measure the wear but in reality that wear will hardly matter at all, because its only seconds for a jump start. When the jump start is only seconds, then that is far to less time for the engine to heat up from reving high, the high reving for the alternator to produce more power will be need only while jump starting the other car and as that is only seconds, then the engine will need likewise to rev only for seconds and that is not enough time for an engine to overheat, even if it was the hottest summer and the waterpump (to circuit the cooling liquid around the engine) was defect.

Why ask us? You were right there. Don't you speak with your Dad? DUH

The battery was flat on one car and so he jump started it using your battery, revving the car brings up your alternator's charging rate

Kar secks probably.