How to write a caption and why captions are important

I learned about captions. Captions are what put context to an image and explain and expand on what is going on in the picture. Without the caption (assuming that the event in the picture shown wasn't too famous), how would you know who is that slapping another person? How would you know what actually happened that caused this to unfold? That is why captions are important. I found out that there were basic captions, which consisted of just the answers questions who, what, when, and where, and I learned about more complex ones that include quotes, are a lot longer, and while the first sentence is in present tense. I also got to get some practice in!