newbie approach: what is a javascript callback function?

Question

Is just a function that executes after one other function that calls it, finishes?

Please I know (almost) nothing about programming, and I find it quite hard to find

Answer 1

Trying to get a more general and simple example, I figured out the following, and with arguments to performe a calculation with two numbers: x and y.

function doMath (x,y,myMath) {return myMath(x,y);}

function mult (a,b){return a*b;}
function sum (a,b){return a+b;}

alert(doMath(2,2,sum))    

where myMath is the callback function. I can replace it for any function I want.