Aristotle, unlike the philosophers before him, broke down the methods of causality (that is cause and effect) into four types of causes. He writes about this in his Physics II.
The first of these causes is the efficient cause. This cause seeks out to answer the question “Who created it?” We can use an example of a house to demonstrate this cause. The carpenter, plumber, and anyone else that built the house would be the efficient cause of the house.
Out of these four causes, the formal and the final causes are probably the hardest to actually define. Since we cannot completely define the designs or essences of things it makes it a harder concept to grasp. Likewise, the final cause deals with purposes. This question has been debated for centuries. Why are humans here, what is their purpose? What is right what is wrong and how does this fit into the meaning of life? Questions like these are much harder to explain.