Of (English preposition)

Primary functions

• Possession or association: "the roof of the house", "the mother of the child".
• Partitive or quantity: "a piece of cake", "some of them".
• Material or composition: "a ring of gold", "a table of glass".
• Origin or source: "a man of Rome", "wine of France".
• Adjectival complements and idioms: "proud of", "afraid of", "of course".

Usage and style

Of frequently serves where a genitive ('s) might also be possible: "the pages of the book" versus "the book's pages." Choice between the forms can depend on rhythm, emphasis, length of the possessor, formality, or clarity. In some constructions the possessive 's is preferred for animate possessors, while of is common for abstract relationships, materials and complex noun phrases.

History and notable points

The preposition has Germanic roots and has long been part of English grammar. Historically it could express meanings now covered by other words (for example older passive constructions such as "beloved of many"). Its flexibility has produced many idioms and set phrases; regional speech also shows reduced pronunciations (e.g. dialectal "o'" in contractions).

Examples and contrasts

Typical examples include: "a cup of tea", "the leader of the group", "a sense of duty", and "maps of the region". When distinguishing from similar prepositions like "from" or verb phrases, context determines whether of indicates origin, composition, or mere association. For further grammatical guidance see resources for the English language.