Function application

Mahdi wrote:
> if it is possible explain it by examples.
We're not doing anyones homework here. Lets try it the other way:
You write down your explanation. And we discuss whether its right 
or wrong. And if the second: what is wrong.

Hi
When we use “ function” and where is its exact usage? what is the 
difference between it and “component”? if it is possible explain it by 
examples.

Thank you

I concatenated your both threads. My statement still keeps its 
validity...