A preposition is a word like on, in, off, about and over. It is normally followed by a noun or pronoun.
- There is a cat on the roof.
- He is fond of children.
- She sat by the fire.
- The lion and the unicorn fought for the crown.
Most English prepositions have several different functions. At the same time, different prepositions can have very similar uses.
When we use verbs after prepositions, we use -ing forms, not infinitives.
- We are thinking of visiting them. (NOT We are thinking of to visit them.)
- He insisted on being paid at once. (NOT He insisted on to be paid at once.)
- I hate the idea of getting old.
- I am not very good at cooking.
When to is a preposition, it is followed by an -ing form.
- I look forward to seeing you soon.
- She objected to my entering her room.
In addition to single-word prepositions like at, in, on, for, to and about, there are certain word groups which function as prepositions.
Examples include in front of, in spite of, by means of, in order to, on behalf of and in the course of .
These word groups are called phrase prepositions or conglomerate prepositions.
A phrase consisting of a preposition followed by a noun phrase, its object. In the following example, all the bracketed sequences are prepositional phrases.
(After the game) several (of the players) went (into the town) (with their wives).