Abstraction is an important concept applied widely to variables, functions, complex data, abstract data types, classes and polymorphism in programming languages. However, the concept of abstraction has been considered as ambiguous and explained differently because it is not defined clearly and uniformly. In this paper, we analyse many aspects of abstraction in programming languages, and propose the taxonomy of abstraction. We classify abstraction according to the mechanism of formation into 4 categories such as napping abstraction, bundling abstraction. integrating abstraction and extending abstraction. We also consider many concepts related closely to abstraction such as functions, abstract data types, objects, encapsulation and classes in the view of abstraction. These analysis and consideration will make it possible to explain uniformly various aspects of abstraction which have been treated individually and differently, and to understand the meanings, necessity and importance of abstraction more intensively.