What is the use of static?

Answer 1

"static" says the function work on its own

Answer 2

static methods and variables are tied to the class, not the object.

There are also static classes which means no instantiation is necessary. (no new objects).

The obvious example of a static method is the main method. It wouldn't make sense to be able to create a new "main" object.

Answer 3

static keyword indicates either it is a class method, class variable.
Remember class cannot be static and final.