Paul Evans: Saving Users From Themselves. As a wide-eyed, innocent new Python programmer, you may naively expect that you can simply ask users for input and they will just give it to you.
Outlines some pitfalls of acquiring input, sanity-checking input (like escaping it properly if it’s going to be displayed on a web page), coercing it into useful forms (examples of phone numbers, postal codes, and social security numbers), and so forth.
