what is philosophy?

The name "philosophy" derives from the Greek for "love of wisdom", but what's that? There has been a long and glorious history of people called philosophers, but they talk about all kinds of topics in all kinds of ways. It is not clear what, if anything, they have in common that makes them all philosophers.
Philosophy's goal is nothing less than a systematic world view. Other fields study particular kinds of things. Philosophy asks how it all fits together. For example, if you want to learn about bodies, take a course in physics or biology. If you want to learn about minds, take a course in psychology. But if you want to learn about how minds are related to bodies, or how physics is related to psychology, then philosophy (of mind) is for you. Similarly, economics, political science, and art and music courses study different values (welfare, justice, and beauty).
Then moral philosophers ask how these values are similar or different, when one may be traded off against another, and where any of these values fit into the physical world. Again, historians try to discover knowledge of the past and astronomers try to discover knowledge of stars and planets, but only philosophers ask what makes any of these beliefs knowledge, and how (or whether) we can have any knowledge at all. Such philosophical questions are very abstract, but that is what enables them to cover so many different fields at once.