Computer Science : Scoping
Scope refers to the visibility of variables, parameters and functions in one part of a program to another part of the same program. In other words, which parts of your program can see or use it. Normally, every variable defined in a program has global scope. Once defined, every part of your program can access that variable. But it is a good practice to limit a variable's scope to a single definition. This way, changes inside the function can't affect the variable on the outside of the function in unexpected ways.