The term "prescriptive grammar" does not refer to one particular
book or theory. There is no single authority on the English language
equivalent to the academies for Spanish and French. So, there are many
different approaches to DEscribing English usage (sometimes called "descriptive
grammar") and PREscribing its correct application.
"Prescriptive grammar" sets forth rules for how the language
should be used (prescriptive) and how it should not be used (proscriptive),
based on a particular formal model of grammar. For English, such a grammar
might prescribe "I" as in "It is I" and proscribe
"me" as in "It's me." It may proscribe "like"
used as a conjunction, as in "He acted like he was the king."
Prescriptive grammar is the set of rules that children learn in school.
It mainly concerns the written languagepunctuation, spelling,
word forms, etc. It provides a general standard that guides writers,
editors, and speakers of English in formal communications.