Type help() for interactive help, or help(object) for help about object.
>>> help()
Welcome to Python 2.7! This is the online help utility.

If this is your first time using Python, you should definitely check out
the tutorial on the Internet at

Enter the name of any module, keyword, or topic to get help on writing
Python programs and using Python modules. To quit this help utility and
return to the interpreter, just type "quit".

To get a list of available modules, keywords, or topics, type "modules",
"keywords", or "topics". Each module also comes with a one-line summary
of what it does; to list the modules whose summaries contain a given word
such as "spam", type "modules spam".

To find out information on a built-in function such as open type open after the help> prompt
help> open
Help on built-in function open in module __builtin__:

open(name[, mode[, buffering]]) -> file object

Open a file using the file() type, returns a file object. This is the
preferred way to open a file. See file.__doc__ for further information.