Determiners refer to words which are used in the premodification of a noun phrase and which typically precede any adjectives that premodify the head word.
In terms of function, they break into two major types: identifiers and quantifiers, each of which may have either definite reference or indefinite reference.
For example:
There is a house in the middle of the street (identifier)
Would you like some tea? (quantifier)(1 point