Definiteness is a feature which can be found in the world's languages and which is commonly expressed by the usage of the definite article. In my thesis, I focuse on two languages, English and Hungarian and compare them on the basis of whether they use the definite article with certain noun classes and noun phrases or not. After a review of the proposals that have been made about definiteness, I look at the similarities of these two languages using the definite article, namely with proper nouns, quantified noun phrases and personal pronouns. By contrast, I survey the differences in the usage of the definite article in Hungarian and English, looking at demonstrative determiners, definiteness of the possessed object and overt personal pronoun possessors.