Does caffeine have beneficial or harmful effects on the body?

Caffeine is harmful to our bodies. It can affect our body if we drink to much. One example is when it was very late and I wanted to finish my homework. However I was feeling very sleepy so I went to drink a few cups of coffee to keep me awake. But the next day, I had a terrible headache and could not go to school. This was the result of me drinking too much of coffee which caused me to have a terrible headache and affected my body physically.