Push Start a Car

If your car has a manual transmission and the battery is dead, you can get it to start by pushing it and quickly releasing or "popping" the clutch.

Steps

Put the car in second gear, and push the clutch all the way in.
Turn the key to the on position.
Get someone to push the car for you, or, if you're lucky enough to be on a hill, just let it roll!
Once the car's rolling, let out the clutch and immediately give the car some gas. The engine should catch, and now you can drive it like you usually would. Just don't let it stall!

The reason that it is usually best to push start it in second gear is because it will be a far smoother start with less of a jolt, so there is less wear on the clutch and transmission. However, if you only have a short distance to push start the car in, or you don't have much speed, first gear may be better.
Release the clutch very quickly; if you ease it out, your engine will not start.
If this doesn't work the first time, give it another shot and let it get going a little faster before you pop the clutch. Which is where the alternate name, pop starting, comes from.

Make sure the person pushing stops when you are trying to start the car. People have been known to break wrists on a car that has stopped suddenly.
When your engine is not running, you don't have power brakes, so be very careful when on a hill not to hit anyone or let the car get out of control.