Of (preposition)

1. Expressing the relationship between a part and a whole.
2. Expressing the relationship between a scale or measure and a value.
3. Expressing the relationship between a direction and a point of reference.
4. Expressing the relationship between a general category and the thing being specified which belongs to such a category.
5. Used to indicate the material or substance something is made from.

Origin:

Old english, of germanic origin; related to dutch and german von, also to off.

Examples:

1. The pages of the book were worn.
2. A quarter of a cup of sugar was needed for the recipe.
3. North of the city lies the river.
4. The capital of Italy is Rome.
5. The statue was made of bronze.