If a constant is created and assigned a value, the value cannot be changed. This is because it's constant data. You can try to change it by writing something like this:
const int Age = 27; Age = 53;
But the compiler will not permit it. For the value to change, it must be a variable. Declaring a variable in C++ is much like declaring a constant. When declaring variables, the keyword const can be omitted. The compiler assumes a variable is being declared unless the const keyword is used. Variables are much more common in programming.
//This is a comment. Notice how the declaration of these variables is //the same as constants, but with no const keywords int Age = 27; int Friend_Age = Age; bool Is_Human = true; float Pi = 3.14; char Letter = 'a'; //These are all variables. They can be changed after declaration too, as //below Is_Human = false; Letter = 'b'; Age = 27 + 3; Friend_Age = Age + 3;