ELI5: Explain Like I'm 5

Predetermined variables

Predetermined variables are numbers or values that are set before you start something. For example, if you are counting from 1 to 10, the predetermined variables are the numbers 1,2,3,4,5,6,7,8,9, and 10. These variables are set before you start counting, so they don't change while you are in the middle of counting.