Articles are divided into two groups:
definite articles (as in the
English article "the") and
indefinite articles (as in the
English "a", "an").
In the Indu-European languages there is an interesting connections between the existance of declensions and the use of articles: the more common is the use of declensions the less the language has need of articles. Thus Latin and Homeric Greek lack articles altogether, whereas Classic Greek uses only definate articles. in German it is the articles themselves which are used as a kind of declension (though some cases - genetive for instance - are still in everyday use).