What is nesting of functions?

Nesting of functions : In C, each function can contain one or more than one function in it. There is no limit as to how deeply functions can be nested. Consider the following example,

function main(){
     function01();
     }

function function01(){
     function02();
     }

function function02(){
     //do something more here.
     }

In the above example, The main() function contains function01(), the function01() contains function02 and so on. This is nesting of functions.