Car starts and runs great, turn it off and have to wait 15-20 minutes to start

What is your question?

This is a 2001 hyundai elantra and starts up great everytime. I can drive it 5 minutes down the road, or 3 hours down the road no problems. But when I shut it off I have to sit and wait 15-20 minutes for it to start again. I turn the key all lights come on and engine turns over and over and will not start. After waiting 15-20 minutes it starts right up and drives off like nothing happened.