What is Philosophy and Fundamental Issues in Philosophy?

Philosophy is a systematized and theorized worldview, a unity of worldview and methodology.

The basic problem of philosophy is the problem of the relationship between thinking and existence. This question includes two aspects: 1. thinking and existence of what is the original, that is, who is the first. 2. thinking and existence have no identity, that is to say, whether the human mind can correctly recognize the existence of the problem.