What is the utility of built-in function help()?

Q. What is the utility of built-in function help()?

Answer =

Python's built-in function help() is very useful. When it is provided with a program-name or a module-name or a function-name as an argument, it displays the documentation of the argument as help. It also displays the doc-strings within its passed-argument's definition.

For example,

help(math)

will display the documentation related to module math.
It can even take function name as argument, e.g.

help(math.sqrt)

The above code will list the documentation of math.sqrt() function only.