A couple days into my first design job, I was ridiculed by the senior staff because I had set some text using the standard straight up-and-down quotes available on the keyboard. The sure sign of an amateur typographer is the improper usage of quotes.
- (") programmer’s quotes (")
- (“ and ”) Curly open and close double typographer’s quotes (“ and ”)
- (‘ and ’) Curly open and close single typographer’s quotes (‘ and ’)
- (« and ») Double angle quotation marks (« and »)
- (′ and ″) Prime and Double Prime (′ and ″)
Basic Rules & Tips
The typewriter substituted upright, direction neutral quotation marks (") for opening and closing marks or typographic quotes (“ and ”, ‘ and ’) in order to save space on the limited keyboard. Proper quotations marks should always be used, and the improper usage should always be looked at as a mistake.
There is almost always a need for designers to manually convert straight quotes to curly quotes in most documents. Most word processors often have a setting for “smart quotes” which will insert the proper quotes in the context of a document, but these are often lost and are not converted to their HTML equivalents when the copy is pasted or imported into a web environment.
Another common mistake and misuse of the upright programmer quotes is their use as prime and double prime characters. These characters are used to indicate feet (′) and inches(″), minutes (′) and seconds(″), and even typographic points (12′ type).
The double angle quotation mark is also often misused as an arrow icon or indicator. The double angle quotations marks (« and ») are used extensively in European languages instead of quotes, although many are adopting the English quoting style.
(Read More Here: http://en.wikipedia.org/wiki/Quotation_mark)