what is user defined function.please explain with examples

Question

function defined by user

Answer 1

it is clear
thank you
but 3rd line.

Answer 2

There are two types of functions:
1.Predefined or inbuilt functions - input(),len(),str(),etc.
2.user defined functions- those functions which we made using keyward 'def' .
example:
def adding(a,b)
return a+b
I hope this may be clear now.