characters that a represented only by the space they take up on a page or screen. The most common examples are space (' '), newline ('
'), and tab (' '). Found on http://www.stroustrup.com/glossary.html
The unconventional use of space characters (' ') to control the flow of a program. Instead of a loosely-enforced ideal, this is an integral part of Python syntax. It's a tradeoff between readability and flexibility in favor of the former. Found on https://wiki.python.org/moin/PythonGlossary