An important role in English grammar is played by determiners – words or phrases that precede a noun or noun phrase and serve to express its reference in the context. The most common of these are the definite and indefinite articles, the and a(n). Other determiners in English include demonstratives such as this and that, possessives such as my and the boy's, and quantifier such as all, many and three.
This is a companion discussion topic for the original entry at http://grammarerror.com/tags/determiner