Abstraction means to describe with a term or a brief sentence that the audience can understand the entirety. In OOPScontext, the program unit is an abstraction by itself. when we use the term"program", we sort of know what it is, yet don't know anything of the detail what it can and will do. Hence, any software element may bethoughtofas an abstraction in OOPS if you do not know the detail implementation!! The element may besmall as a method, a property, a class, an interface, and up to the entire application/program itself.