Variable is a named value that can be changed (varies). Variables can be created in several different ways:
A typical use case for variable is when you have an object that can be in several states. For example, a door can be open or closed, and if you want to animate it properly you need to know in which exactly status it is now.
This puzzle assigns a value to a variable.
This puzzle provides the value stored in a variable, without changing it.
Increments the value stored in a variable by a specified number. If the initial value is not numeric, or not set, then it is considered to be zero which is incremented.