Abstraction is a technique for dealing with complexity. It works by establishing a level of complexity we are interested in, and suppressing the more complex details below that level.
The guiding principle of abstraction is that only details that are relevant to the current perspective or the task at hand needs to be considered. As most programs are written to solve complex problems involving large amounts of intricate details, it is impossible to deal with all these details at the same time. That is where abstraction can help.
Ignoring lower level data items and thinking in terms of bigger entities is called data abstraction.
Within a certain software component, we might deal with a user data type, while ignoring the details contained in the user data item such as name, and date of birth. These details have been ‘abstracted away’ as they do not affect the task of that software component.
Control abstraction abstracts away details of the actual control flow to focus on tasks at a simplified level.
print(“Hello”) is an abstraction of the actual output mechanism within the computer.
Abstraction can be applied repeatedly to obtain progressively higher levels of abstractions.
An example of different levels of data abstraction: a File is a data item that is at a higher level than an array and an array is at a higher level than a bit.
An example of different levels of control abstraction: execute(Game) is at a higher level than print(Char) which is at a higher than an Assembly language instruction MOV.
Abstraction is a general concept that is not limited to just data or control abstractions.
Some more general examples of abstraction: