Invocation

Running a function, in Javascript, by using parenthesis();

function b() {
}

function a(){
    b(); 
}

a(); 

//So what is really happening? 
- The Global Execution Context (Created and code is executed) 
- Will attach those function (a and b) to the window object
- When it hits a(), it creates a new execution context, called the 'execution stack'
- Anytime you execute a function, a new 'execution context' is created and put on the 'execution stack' 
- So the 'execution context' is created like the global one, so it will have its own space for variable and functions
- However if we have another function invocation and create a new Execution Context.

Every time a function is invoked, a new execution context is created, put on top of the stack and when it finishes, it gets popped off.

Its run line by line, synchronously.