A preposition is used to link noun, pronouns and phrases to other words in a sentence. The word or phrase that the preposition introduces is called the object of the preposition. A preposition is used to indicate the temporal, spatial or logical relationship of its object to the rest of the sentence. Here are some examples:
The pencil is ON the desk.
The pencil is BENEATH the desk.
The pencil is leaning AGAINST the desk.
The pencil is on the floor BESIDE the desk.
He held the pencil OVER the desk.
He wrote with the pencil DURING class.
You may have noticed that in each of the preceding sentences, the preposition located the noun "pencil" in space or in time.
Here are some general rules regarding prepositions:
• It is permissible to end a sentence with a preposition.
• A preposition is followed by a noun.
• A preposition is never followed by a verb.
• It is permissible to begin a sentence with a preposition, or a prepositional phrase, but be very careful when you do so.*
• A prepositional phrase always begins with a preposition and ends with a noun or pronoun called the OBJECT of the preposition.
• The subject of the sentence can never be part of a prepositional phrase.
• A verb can never be a part of a prepositional phrase.
There is a so-called “rule” about never ending a sentence with a preposition and it comes from Latin grammar. In Latin grammar, the word order of a sentence didn't matter; subjects and verbs and direct objects could appear in any sequence. However, the placement of prepositions was very important. A Latin sentence would quickly become confusing if the preposition did not appear immediately before the object of the preposition, so it became a stylistic rule for Latin writers to have objects always and immediately following prepositions. This Latin grammar "rule" meant that a sentence would never end with a preposition.
When English grammarians in the 1500s and 1600s starting writing grammar books, they tended to apply Latin rules to English, even though those rules had never been applicable before. I believe that they wanted to make English a more scholarly language, like Latin.
Here is a list of some prepositions:
by the time of
in front of
in spite of
in view of
on top of
* This is a “rule” that been questioned for many years. Many writers actually do start sentences with prepositions and many college professors have no problems with it. The reason for the “rule” was that a preposition usually indicates the temporal, spatial or logical relationship of its object to the rest of the sentence. Therefore if you start a sentence with a preposition it can appear that you are in the middle of a sentence or thought. If you are careful however, you can start a sentence with a prepostion. The problem is that most people are not careful. Here is an example of a sentence that starts with a prepostition that works: Before going to the store, I always check my list. Many people use prepositions incorrectly at the beginning of a sentence, therefore, the “rule” came to be. You can think of it as more of a “suggestion” than a rule. When you are writing a paper for a school project, it is safer to use the rule.
There is a right way and a wrong way to start a sentence with a preposition. Many authors and writers start some of their sentences with prepositions and it works very well for them. You simply have to be careful when starting a sentence with a prepostion, that the sentence does not become fragmented as a reuslt.
Here is an example with the preposition up.
Correct usage: We ran up the hill.
Incorrect: Up the hill we ran.
Here is an example with the preposition over.
Correct: The rabbit jumped over the log.
incorrect: Over the log the rabbit jumped.
Here is an example with the preposition aboard.
Correct: We got aboard the train to ride down to San Diego.
Incorrect: Aboard the train we got to ride down to San Diego.
Examples of prepositions at the beginning of a sentence:
Despite the rain, we still went jogging. Barring any setbacks, the quarterback will play in the next game. In spite of all the harm it causes, people still smoke cigarettes.
Remember that prepositions are connecting words and are generally used to connect a noun or pronoun to another word in a sentence.
Beware of the phrase “in terms of” and do not use it. This phrase is a sloppy use of prepositions that should be avoided. Strunk & White, in their book The Elements of Style recommend that this phrase not be used used. They give this example: The job was unattractive in terms of salary. Instead use: The salary made the job unattractive.