The goal of this literature study is to give some preliminary answers to the questions that aim to uncover the Pedagogical Content Knowledge (PCK) of Informatics Education, with focus on Programming. PCK has been defined as the knowledge that allows teachers to transform their knowledge of the subject into something accessible for their students. The core questions to uncover this knowledge are: what are the reasons to teach programming; what are the concepts we need to teach programming; what are the most common difficulties/misconceptions students encounter while learning to program; and how to teach this topic. Some of the answers found are, respectively: enhancing students' problem solving skills; programming knowledge and programming strategies; general problems of orientation; and possible ideal chains for learning computer programming. Because answers to the four questions are in a way not connected with each other, PCK being an unexplored field in Informatics Education, we need research based efforts to study this field.