Of

Of is a widely used English preposition that marks a relationship between two elements. It expresses origin or source, possession, composition or material, content or theme, partitive meaning, and association. It is common in both everyday speech and formal writing, and it often appears in noun phrases, clauses, and idiomatic expressions.

Common uses include indicating material: a statue of marble; content: a cup of tea; quantity or partitive meaning: three of us; origin or association: a man of wealth; characteristic: a woman of courage; and reference: a book of poetry. It also appears in expressions denoting membership, hierarchy, or attribution, such as “a member of the committee” or “the capital of France.” In many cases, the sense can be conveyed by the possessive form (the car’s color, for example), but of tends to be preferred for inanimate nouns, abstract nouns, and official titles or formal descriptions.

In syntax, of links the preceding noun to the following noun to form a prepositional phrase. Its placement can affect emphasis and nuance, as in “the door of the house” versus “the house’s door.” Some fixed phrases and idioms depend on of in ways that resist straightforward paraphrase with a possessive, such as “free of charge,” “out of reach,” or “pieces of eight.”

Etymology traces of the word go back to Old English in the same form, with cognates across early Germanic languages. As one of the oldest and most versatile prepositions in English, of remains essential for expressing a broad range of relational meanings.