This is a great video from the American Chemical Society with facts about caffeine. Lots more entertaining than the sort of video you may have seen in school.
Caffeine is found in some of the high potassium beverages, such as coffee and tea. But caffeine has some favorable effects of its own. I've seen lots of research papers over the years try to find harm from caffeine. All but a handful were unsuccessful. And those that found harm were always later refuted.
The video explains how caffeine keeps you alert and helps athletic performance. They didn't explain it improves muscle strength though. That would have been nice to include.
We have discussed here how drinking up to at least 6 cups of coffee a day has health advantages. This video only recommends 3 cups of coffee on average. But it also explains that the caffeine in coffee does not become toxic until you drink 75 cups in a day. So there is plenty of safety margin in coffee. Enjoy the video.