Below you’ll find a comprehensive explanation of prepositions taken from GRAMMAR BYTES (http://www.chompchomp.com/terms/preposition.htm)
If you’re interested in more visual explanations, check out this video:
Recognize a preposition when you see one.
Prepositions are the words that indicate location. Usually, prepositions show this location in the physical world. Check out the three examples below:
The puppy is onthe floor.
The puppy is in the trash can.
The puppy is besidethe phone.
On, in, and beside are all prepositions. They are showing where the puppy is. Prepositions can also show location in time. Read the next three examples:
At midnight, Jill craved mashed potatoes with grape jelly.
In the spring, I always vow to plant tomatoes but end up buying them at the supermarket.
During the marathon, Iggy’s legs complained with sharp pains shooting up his thighs.
At midnight, in the spring, and during the marathon all show location in time.
Because there are so many possible locations, there are quite a few prepositions. Below is the complete list.
by means of
in addition to
in back of
in case of
in front of
in place of
in spite of
on top of
* But is very seldom a preposition. When it is used as a preposition, but means the same as except—Everyone ate frog legs but Jamie. But usually functions as a coordinating conjunction.
Understand how to form a prepositional phrase.
Prepositions generally introduce prepositional phrases. Prepositional phrases look like this:
Preposition + Optional Modifier(s) + Noun, Pronoun, or Gerund
Here are some examples:
At = preposition; school = noun.
According to us
According to = preposition; us = pronoun.
By = preposition; chewing = gerund.
Under the stove
Under = preposition; the = modifier; stove = noun.
In the crumb-filled, rumpled sheets
In = preposition; the, crumb-filled, rumpled = modifiers;sheets = noun.
Realize that some prepositions also function as subordinate conjunctions.
Some prepositions also function as subordinate conjunctions. These prepositions are after, as, before, since, and until. A subordinate conjunction will have both a subject and a verb following it, forming a subordinate clause.
Look at these examples:
After Sam and Esmerelda kissed goodnight
After = subordinate conjunction; Sam, Esmerelda = subjects; kissed = verb.
As Jerome buckled on the parachute
As = subordinate conjunction; Jerome = subject; buckled = verb.
Before I eat these frog legs
Before = subordinate conjunction; I = subject; eat = verb.
Since we have enjoyed the squid eyeball stew
Since = subordinate conjunction; we = subject; have enjoyed = verb.
Until your hiccups stop
Until = subordinate conjunction; hiccups = subject; stop = verb.
If you find a noun [with or without modifiers] following one of these five prepositions, then all you have is a prepositional phrase. Look at these examples:
After the killer calculus test
After = preposition; the, killer, calculus = modifiers; test = noun.
As a good parent
As = preposition; a, good = modifiers; parent = noun.
Before = preposition; dinner = noun.
Since the breakup
Since = preposition; the = modifier; breakup = noun.
Until = preposition; midnight = noun.