In many languages, articles are a special part of speech which cannot be easily combined[clarification needed] with other parts of speech. In English grammar, articles are frequently considered part of a broader category called determiners, which contains articles, demonstratives (such as "this" and "that"), possessive determiners (such as "my" and "his"), and quantifiers (such as "all" and "few"). Articles and other determiners are also sometimes counted as a type of adjective, since they describe the words that they precede.
In languages that employ articles, every common noun, with some exceptions, is expressed with a certain definiteness, definite or indefinite, as an attribute (similar to the way many languages express every noun with a certain grammatical number—singular or plural—or a grammatical gender). Articles are among the most common words in many languages; in English, for example, the most frequent word is the.
Articles are usually categorized as either definite or indefinite. A few languages with well-developed systems of articles may distinguish additional subtypes. Within each type, languages may have various forms of each article, due to conforming to grammatical attributes such as gender, number, or case. Articles may also be modified as influenced by adjacent sounds or words as in elision (e.g., French "le" becoming "l'" before a vowel), epenthesis (e.g., English "a" becoming "an" before a vowel), or contraction (e.g. Irish "i + na" becoming "sna").
The definite article is used to refer to a particular member of a group or class. It may be something that the speaker has already mentioned or it may be something uniquely specified. There is one definite article in English, for both singular and plural nouns: the:
The children know the fastest way home.
The sentence above refers to specific children and a specific way home; it contrasts with the much more general observation that:
Children know the fastest ways home.
The latter sentence refers to children in general and their specific ways home. Likewise,
Give me the book.
refers to a specific book whose identity is known or obvious to the listener; as such it has a markedly different meaning from
Give me a book.
which uses an indefinite article, which does not specify what book is to be given.
The definite article can also be used in English to indicate a specific class among other classes:
The cabbage white butterfly lays its eggs on members of the Brassica genus.
However, recent developments show that definite articles are morphological elements linked to certain noun types due to lexicalization. Under this point of view, definiteness does not play a role in the selection of a definite article more than the lexical entry attached to the article.[clarification needed]