What Is Causation?

i've been intrigued by existential philosophy. Life is meaningless, right? You know, go down the list of sartra and an heydeger and blababla am. The problem with with certain philosophies they stop there. And it's your obligation as a human being to figure out then what? So if life is meaningless. It's up to you to create your own meaning. Am the other philosophical um aspect of life is understanding causation. Understanding the basic concept of causation is massive. Amazing how many people don't get that.