Aristotle came up with four basic questions that could be asked about things. These he called aitia, which doesn't translate well at all. They are almost always translated as 'causes'.
1. You might want to know what something is made of, or its material cause.
2. You might whant to know about its form or structure, its formal cause.
3. You might want to know about how it began or was made, its efficient cause.
4. You might want to know about its purpose or goal, its telos or its final cause.