Economics Homework Help

I’m working on a finance writing question and need an explanation and answer to help me learn.

Please write a few sentences to explain 1)what is crude oil future? 2)why did the oil future price turn negative?

(Running out of oil storage tanks could be a reason) It would be great if you can attach related charts.

https://www.bloomberg.com/news/articles/2020-04-20/negative-prices-for-oil-here-s-what-that-means-quicktake