A determiner is a member of a word class of great importance to fluent idiomatic English. Non-native speakers find some aspects of this group among the hardest aspects of English usage to learn. They are divided into three categories, which must occur in this order: predeterminers, central determiners and postdeterminers. The most important are the central determiners.
- Central determiners include the articles, the possessive pronouns, and such words as 'this', 'that', 'every', 'each' and the negatives 'no' and 'neither' are also central determiners. A noun phrase can have only one of these central determiners.
- Predeterminers, of which a noun phrase can only have one, include numerical words like 'all', 'both' and 'half', as well as fractions like 'one-third (of)' and multipliers like 'double'.
- Postdeterminers include numerals, both cardinal and ordinal, and some others.