Definition - Sometimes words that come before a noun and modify it in some way are called 'determiners'. Articles, adjectives, pronouns, and other words can be used as determiners. Examples:

The Spanish demonstrative 'este [this]' is used as a determiner to show 'position' in the following sentence:
             • Este hombre aquí es muy alto. [This man here is very tall.]

The Spanish possessive 'mi [my]' is used as a determiner to indicate 'possession' in this sentence:
             • Estás leyendo mi revista. [You are reading my magazine.]