In a selection structure, a question is asked, and depending on the answer, the program takes one of two courses of action, after which the program moves on to the next event.

This structure is sometimes referred to as an if-then-else because it directs the program to perform in this way: If Condition A is True then perform Action X else perform Action Y.

All logic problems in programming can be solved by forming algorithms using only the three logic structures, and they can be combined in an infinite number of ways. The more complex the computing need, the more complex the combination of structures.