What is execution context?

 When a JavaScript functions call then an execution context is put on top of the execution stack. Below is the structure of a execution context object.

--Variable object(VO): All the parameters are passed to a function is stored in VO. Function declaration is stored into VO to pointing a function. Variables are scanned and for all variable a property is created in VO and set to undefined which is called hoisting .Hoisting means they are available before execution.We will know more about in the next.