Could you tell me...?

I want to know the difference between descriptive grammars and prescriptive grammars. Could you give me some examples to explain the difference?
Thank you

Descriptive grammars attempt to describe the language people actually use, rather than tel them what they should say, so it would look at and analyse forms like 'ain't' without judging them as wrong. A prescriptive grammar would classify that as an error. ;-)

http://www.usingenglish.com/glossary...e-grammar.html
http://www.usingenglish.com/glossary...e-grammar.html
;-)