Prepositions are us

You can write wonderfully without knowing a great deal about grammar or, for instance, what a preposition is. Well, you can, but you'll be an even better writer if you know a few odds and sods to give your work colour, texture and verve. So. A preposition links nouns, pronouns and phrases and usually indicates the temporal, spatial or logical relationship of its object to the rest of the sentence as in the following examples:

The book is on the table.

The book is beneath the table.

The book is leaning against the table.

The book is beside the table.

She held the book over the table.

She read the book during class.

So now you know what one is, try writing without any. For 10 minutes.