Prepositions are relation words; they can indicate location, time, or other more abstract relationships. Prepositions are noted in bold in these examples:

• The woods behind my house are creepy at night.
• She studied until three in the morning.
• He was happy for them.

A preposition combines with another word (usually a noun or pronoun) called the complement. Prepositions are still in bold, and their complements are in italics:

• The woods behind my house are creepy at night.
• She studied until three in the morning.
• He was happy for them.

Prepositions generally come before their complements (e.g., in England, under the table, of Jane). However, there are a small handful of exceptions, including notwithstanding and ago:

• Financial limitations notwithstanding, Phil paid back his debts.
• He was released three days ago.

Prepositions of location are pretty easily defined (near, far, over, under, etc.), and prepositions about time are as well (before, after, at, during, etc.). Prepositions of “more abstract relationships,” however, are a little more nebulous in their definition. The video below gives a good overview of this category of prepositions:

So far, all of the prepositions we’ve looked at have been one word (and most of them have been one syllable). The most common prepositions are one-syllable words. According to one ranking, the most common English prepositions are on, in, to, by, for, with, at, of, from, as.

There are also some prepositions that have more than one word:

• in spite of (She won the election in spite of gerrymandering.)
• by means of (They filtered the water by means of porous membranes.)
• except for (The prices of all commodities spiked except for oil.)
• next to (The cell phone tower is next to a busy mall.)

Using Prepositions

A lot of struggles with prepositions come from trying to use the correct preposition. Some verbs require specific prepositions. Here’s a table of some of the most commonly misused preposition/verb pairs:

Some verbs take a different preposition, depending on the object of the sentence:

When multiple objects take the same preposition, you don’t need to repeat the preposition. For example, in the sentence “I’ll read any book by J. K. Rowling or R. L. Stine,” both J. K. Rowling and R. L. Stine are objects of the preposition by, so it only needs to appear once in the sentence. However, you can’t do this when you have different prepositions, as in the common phrase “We fell out of the frying pan and into the fire.” If you leave out one of the prepositions, as in “We fell out of the frying pan and the fire,” the sentence is saying that we fell out of the frying pan and out of the fire, which would be a preferable fate, but isn’t the point of this idiom.

Prepositions in Sentences

You’ll often hear about prepositional phrases (especially if you and your friends like to read grammar guides). A prepositional phrase includes a preposition and its complement (e.g., “behind the house” or “a long time ago“). These phrases can appear at the beginning or end of sentences. When they appear at the beginning of a sentence, they typically need a comma afterwards:

• You can drop that off behind the house. Behind the house, there’s a covered porch.
• A long time ago, dinosaurs roamed the earth. Pterodactyls ruled the air a long time ago.

Ending a Sentence with a Preposition

As we just learned, it is totally okay to end a sentence with a preposition. And, as we saw, it can often make your writing smoother and more concise to do so.

However, it’s still best to avoid doing it unnecessarily. If your sentence ends with a preposition and would still mean the same thing without the preposition, take it out. Consider:

• Where are you at?
• That’s not what it’s used for.

If you remove at, the sentence becomes “Where are you?” This means the same thing, so removing at is a good idea. Not only is the preposition redundant, but it also changes the register of the sentence to colloquial; you might say “Where are you at?” but you shouldn’t write it in the fairly formal register of standard English.

On the other hand, if you remove for, the next sentence becomes “That’s not what it’s used,” which doesn’t make sense.

Another common issue with prepositions is piling too many into a sentence, often including an additional one at the end: “With which acid am I supposed to mix the water with?” Again, this unconventional use in standardized English tends to occur when students are out of their comfort zone: here, the relationship between the water and some acid isn’t clear, or the student is unclear on the instructions, or the student is nervous that something is about to explode, and the language is reflecting that unease.