What is philosophy? This is a notoriously difficult question. One of the easiest ways of answering it is to say that philosophy is what philosophers do, and then point to the writings of Plato, Aristotle, Descartes, Hume, Kant, Russell, Wittgenstein, Sartre, and other famous philosophers. However, this answer is unlikely to be of much use to you if you are just beginning the subject, as you probably won't have read anything by these writers.

Philosophy : the basics (Fifth Edition, 2013) - Introduction