In this chapter, an in-depth analysis of the AGM model is presented, elaborating on its core postulates that define rational belief change. Detailed discussions cover mechanisms such as partial meet operations, kernel contractions and revisions, and epistemic entrenchment-based belief change operations. Furthermore, the chapter examines the AGM model through possible worlds semantics, illustrating how belief change is represented using systems of spheres and pre-orders. This chapter provides a comprehensive introduction to the logic of belief change, offering a thorough explanation of the AGM model with clear examples to illustrate its concepts and applications. It serves as a useful resource for researchers embarking on the study of belief dynamics.