How to explain callbacks in plain english? How are they different from calling one function from another function?

Question

How to explain callbacks in plain English? How are they different from calling one function from another function taking some context from the calling function? How can thei

Answer 1

You have some code you want to run. Normally, when you call it you are then waiting for it to be finished before you carry on (which can cause your app to go grey/produce a spinning time for a cursor).

An alternative method is to run this code in parallel and carry on with your own work. But what if your original code needs to do different things depending on the response from the code it called? Well, in that case you can pass in the name/location of the code you want it to call when it's done. This is a "call back".

Normal code: Ask for Information->Process Information->Deal with results of Processing->Continue to do other things.

With callbacks: Ask for Information->Process Information->Continue to do other things. And at some later point->Deal with results of Processing.