Epistemology is the area of philosophy that is concerned with knowledge. The main concerns of epistemology are the definition of knowledge, the sources of knowledge (innate ideas, experience, etc.), the process of acquiring knowledge and the limits of knowledge. Epistemology considers that knowledge can be obtained through experience and/or reason.
A primary concern of epistemology is the very definition of knowledge itself. The traditional definition, since Plato, is that knowledge is justified true belief, but recent evaluations of the concept have shown supposed counterexamples to this definition.
In order to fully explore the nature of knowledge and how we come to know things, the various conceptions of what knowledge is must first be understood.
The sources of knowledge must also be considered. Perception, reason, memory, testimony, introspection and innate ideas are all supposed sources of knowledge. Are they equally reliable?
There also seems to be reason to doubt each of these sources of knowledge. Could it be that all knowledge is fallible? If that is the case, do we really know anything? This is the central question to the problem of scepticism.