Determiners can serve a variety of purposes in sentences and can have different meanings. However, in general, all determiners are used to clarify a noun or a noun phrase. One of the most common functions of determiners is to define or demonstrate an object or a person. For instance, it can show whether the noun that is mentioned in the sentence is something specific or unspecific. Another common purpose of this grammatical form, is that it can also indicate the differences between nouns.
Although there are also other functions of determiners such as for expressing quantity, possession, and questions, most of these purposes are related to the two key areas mentioned earlier. It is not that difficult to understand determiners because they are commonly used in written and verbal English. In order to fully grasp the concept, it is also advisable to study about the different types of determiners which are presented in the next section.