Answer 1

Its a function that call itself.
Real world example, think that i am a function. What i do ? For example my boss told me to move boxes from roomA to roomB.
But each time i move a box to roomB i keep telling myself to go back to roomA and move the box from there to roomB.
That basicly it. My boss dont need to tell me again to move the boxes because i already tell myself to.