Epistemology is the theory of knowledge. It has been occupying a very central position in philosophy since the ancient philosophy, and has even been regarded as the “first philosophy”since R. Descartes in the modern philosophy. In the contemporary development, Epistemology has a new face and a new focus. The theory of justification starts to rise in this subject and overwhelmingly dominates the main stage in the discussions of the subject. So, the nature of knowledge and the nature of justification naturally stand out as two main issues to which almost all philosophers interested in epistemology must pay attention. In this course, we will spend most of our time in pursuing the answers to the questions regarding “what is knowledge?” and “what is justification?”, and will also cover many related important problems and puzzles associating with the two main questions. In order to approach the central concerns in the issues, we will follow step by step the problems raised in the required textbook, Pritchard's Knowledge. Those problems will include: (1) What can we know? This is an introductory question, and with this question we will be familiar with some important and basic concepts and terminology involved in epistemology. (2) Can we really know? This is a skeptical question, and following this question we will learn some skeptical tradition as well as modern skepticism. (3) How can we know the external world? This is a traditional question and the most important question in modern philosophy. We will discuss how the modern philosophers dealt with the concept of “perception” and shed light on the question. (4) What is knowledge? We will start with the traditional analysis and introduce the Gettier problem. (5) What is Justification? We will go through the contemporary discussions with respect to the issue of justification and the foundationalism/coherentism and internalism/externalism debates.