Instead of being treated as a single, unified subject, philosophy is typically broken down into a number of specialties and it is common for contemporary philosophers to be experts in one field but know little about another. After all, philosophy addresses complex issues from all facets of life - being an expert on all of philosophy would entail being an expert on all of the most fundamental questions which life has to offer.
This doesn't mean that each branch of philosophy is entirely autonomous - there is often much overlap between some fields, in fact. For example, political and legal philosophy often cross with ethics and morality, while metaphysical questions are common topics in the philosophy of religion. Sometimes even deciding which branch of philosophy a question properly belongs in isn't very clear.
This is the study of beauty and taste, whether in the form of the comic, the tragic, or the sublime. The word comes from the Greek aisthetikos, "of sense perception." Aesthetics has traditionally been part of other philosophical fields like epistemology or ethics but it started to come into its own and become a more independent field under Immanuel Kant.
Epistemology is the study of the grounds and nature of knowledge itself. Epistemological studies usually focus upon our means for acquiring knowledge; thus modern epistemology generally involves a debate between rationalism and empiricism, or the question of whether knowledge can be acquired a priori or a posteriori.
Ethics is the formal study of moral standards and conduct and is also often called "moral philosophy." What is good? What is evil? How should I behave - and why? How should I balance my needs against the needs of others? These are some of the questions asked in the field of ethics.
Logic and the Philosophy of Language
These two fields are often treated separately, but they are close enough that they are presented together here. Logic is the study of methods of reasoning and argumentation, both proper and improper. The Philosophy of Language involves the study of how our language interacts with our thinking.
In Western philosophy this field has become the study of the fundamental nature of all reality - what is it, why is it, and how are we to understand it. Some only regard metaphysics as the study of "higher" reality or the "invisible" nature behind everything, but that isn't actually true. It is, instead, the study of all of reality, visible and invisible.
Philosophy of Education
This field deals with how children should be educated, what they should be educated in, and what the ultimate purpose of education should be for society. This is an often neglected field of philosophy and is often addressed only be in educational programs designed to train teachers - in that context, it is a part of pedagogy, which is learning how to teach.
Philosophy of History
The Philosophy of History is a relatively minor branch in the field of philosophy, focusing on the study of history, writing about history, how history progresses, and what impact history has upon the present day. This is can be referred to as the Critical, Analytical, or Formal Philosophy of History, as well as the Philosophy of Historiography.
Philosophy of Mind
The relatively recent specialty known as Philosophy of Mind deals with the consciousness and how it interacts with the body and the outside world. It asks not only what mental phenomena are and what gives rise to them, but also what relationship they have to the larger physical body and the world around us.
Philosophy of Religion
Sometimes confused with theology, the Philosophy of Religion is the philosophical study of religious beliefs, religious doctrines, religious arguments and religious history. The line between theology and the philosophy of religion isn't always sharp because they share so much in common, but the primary difference is that theology tends to be apologetical in nature, committed to the defense of particular religious positions, whereas Philosophy of Religion is committed to the investigation of religion itself rather than the truth of any particular religion.
Philosophy of Science
This is concerned with how science operates, what the goals of science should be, what relationship science should have with society, the differences between science and other activities, etc. Everything that happens in science has some relationship with the Philosophy of Science and is predicated upon some philosophical position, even though that may be rarely evident.
Political and Legal Philosophy
These two fields are often studied separately, but they are presented here jointly because they both come back to the same thing: the study of force. Politics is the study of political force in the general community while jurisprudence is the study of how laws can and should be used to achieve political and social goals.