Programs are usually run (executed) one command after the other. e.g.

Command 1
Command 2
Command 3
...

This is fine for most applications. If the program needs to respond to user input or execute different code each time it is run, however, then some form of decision problem is necessary.

Flow Control decides whether or not certain parts of the program should be executed.

Types of Flow Control

There a five types of flow control...

If
For
While
Repeat
Goto

...each of these allow different sequences of code to be executed.