J. P. Moreland provides a good overview of epistemology (how we know) in this post.
First, he defines knowledge (to represent reality in thought or experience the way it really is on the basis of adequate grounds).
Next, he offers three important clarifications about knowledge: (1) knowledge has nothing to do with certainty or an anxious quest for it; (2) one can know something without knowing how one knows it; (3) one can know without knowing that one knows.
Third, he suggests three difference types of knowledge: (1) knowledge by acquaintance (happens when we are directly aware of something); (2) propositional knowledge (knowledge that an entire proposition is true); (3) know-how (the ability to do certain things for certain purposes).