Subject

1. What is the Subject of a Sentence?

A subject is the person, place, idea, or thing that a sentence is about. It’s the noun that is “doing” something in the sentence. Every sentence needs at least one to function properly—otherwise, the sentence wouldn’t be about anything! So, they are absolutely crucial to writing and speaking in English. In fact, subjects might be the most important parts of sentences.

To find a sentence’s subject, usually all you have to ask is: what is this sentence about? Many sentences have only one subject, but they can also have two or more. Sometimes the subject is only one word, called a simple subject; sometimes subjects share a verb and become a compound subject; or sometimes they include other descriptive words, called a complete subject.

2. Examples of Subjects

Every sentence has at least one subject, and it can be almost anything. Because they are the focus, subjects usually come at the beginning of a sentence; many times they are the first word or words. The subjects are underlined in the examples below:

I really love the county fair. “I” as subject
He doesn’t like popcorn. “He” as subject
The dog loves popcorn. “the dog” as subject
Sally and Sam went to the fair together. “Sally” and “Sam” as subjects
County fairs always have popcorn stands. “County fairs” as subject
Dogs love popcorn, but cats like soda. “dogs” and “cats” as subjects

3. Parts of Subjects

Sometimes a subject is only one word, but sometimes it includes modifiers, or can be a noun phrase or gerund. Let’s start with this sentence:

The dog ate the popcorn. Subject = “dog”

Modifiers

A modifier is an adjective or adverb that “modifies” other words in a sentence to make it more descriptive. A subject with a modifier gives you a clearer idea of the noun that the sentence is about. Here’s an example:

The fat dog ate the popcorn. Subject = “fat dog”

This sentence includes the modifier “fat” to better describe the dog.

a. Noun Phrases

A phrase is a group of two or more words that work together but don’t form a clause; and a noun phrase has a noun or pronoun as the main word, and acts like a noun in a sentence. Since it acts like a noun, a noun phrase can be the subject of a sentence, like this:

The fat dog with brown fur ate all the popcorn. Subject = “the fat dog with brown fur”

So, this sentence is about “the fat dog with brown fur,” not just any dog. Here, the phrase “the fat dog with brown fur” works like a noun. You could easily replace this phrase with only “the dog,” but using a phrase better describes the dog and the situation.

b. Gerunds

A gerund is a word that ends in “ing” but functions as a noun in a sentence, NOT as a verb. Because gerund and gerund phrases work like nouns, they can also be subjects, like this:

Eating is my dog’s favorite hobby. Subject = gerund “eating”

Eating popcorn is my dog’s favorite hobby. Subject = gerund phrase “eating popcorn”

Remember, a gerund works like a noun, not a verb!

3. Types of Subjects

Sometimes the subject of a sentence can’t be as simple as one word, so we need different types in order to be able to say what we mean. There are three main types of subjects: simple, compound, and complete.

a. Simple Subject

A simple subject is the main word that tells what a sentence is about. It does not include modifiers or other words. Here are some examples:

Sally went to the county fair. Person as subject
The fair was famous for its popcorn. Place as subject
The hot popcorn was buttery. Thing as subject

A sentence can have more than one simple subject, if they have their own verbs (green):

Sally went to the county fair, and Sam drove to the market. Subjects “Sally” and “Sam”
The dog ate popcorn, and the cat drank Subjects “dog” and “cat”
The popcorn smelled buttery, and the soda tasted Subjects “popcorn” and “soda”

As you can see, each of the subjects has their own verb. For instance, the first sentence has the simple subjects “Sally” and “Sam,” but Sally “went” and Sam “drove.” So, while they are both subjects, they are each doing their own thing.

If two or more subjects use the same verb, then the sentence has a compound subject.

b. Compound Subject

When two or more subjects in a sentence share the same verb, it makes a compound subject:

Sally and Sam went to the county fair.
The dog and the cat ate popcorn.
The popcorn and the soda are delicious.

For a compound subject to occur, the subjects MUST share the same verb. In the first sentence above, both Sally and Sam do the same thing: they “went” to the county fair. Since they both did the same thing, they can share one verb. Without a compound subject, the sentence would look like this:

Sally went to the county fair, and Sam went to the county fair.

You can see that this sentence is unnecessarily long. We don’t need to say these two things separately, which is why we have compound subjects.

c. Complete Subject

A complete subject is made up of all of the words that tell what a sentence is about, including modifiers:

The fat dog with brown fur ate all of the popcorn.
The big dog and the small cat went to the county fair.
Silly Sally and her best friend Sam drove to the fair.

All of these sentences include modifiers that add to the subject. Let’s look more closely at the third sentence:

Silly Sally and her best friend Sam drove to the fair.

Here, the simple subjects are Sally and Sam. But, the sentence also includes the modifier “silly” to describe Sally, and the noun phrase “her best friend Sam” to describe her friend. So, the complete subject of the sentence includes all of the words that make up the subject. If we ask the question “what is this sentence about?”, our answer is the two subjects “Silly Sally and her best friend Sam.”

4. How to Avoid Mistakes with Subjects

As you now know, the subject is the main thing a sentence is about, and all sentences need one. But, what’s more, all subjects need a verb to show an action that is being done. So remember, a subject is nothing without its verb, and a sentence doesn’t exist without its subject!

Furthermore, you want to be sure not to mistake an object or prepositional phrase for a subject.

a. Objects

It’s important to be able to distinguish between the subject and an object in a sentence. Sometimes it can be confusing, so remember this rule: a subject “does” the verb, and an object “gets” the action of the verb. Let’s look at this sentence:

The dog is cooking popcorn for the cat.

This sentence has only one subject: the dog. That’s because the dog “does” the action “cooking.” The cat is NOT a subject—it is an object, because it “gets” the popcorn. Let’s try another:

The dog danced for the rabbit, and the cat slept.

Here, there are two subjects, the dog and the cat, and one object, rabbit. The dog does the dancing, the rabbit gets to see the dancing, and the cat does the sleeping.

b. Prepositional Phrases

A preposition is a word that indicates location, like in, at, with, on, beside, before, after, to name a few. Prepositional phrases combine a preposition with a noun. Like subjects, they often come at the beginning of the sentence, but, they are NOT the subject—they only give details.

Here are some examples:

The dog went to the county fair. Subject = dog

Last night, the dog went to the county fair. Subject = dog

The dog cooked popcorn. Subject = dog

At home, the dog cooked popcorn. Subject = dog

Adding a prepositional phrase does not affect a sentence’s subject. The prepositional phrases just add details about the subject itself, they do NOT work like nouns, and can’t be the sentence’s subject. An easy trick to remember is that the prepositional phrase can usually be switched to the end of the sentence:

The dog went to the county fair last night.

BUT, you couldn’t do the same thing with a subject, like this:

Went to the county fair the dog. Incorrect!

Now, let’s review!

To find a sentence’s subject, you just need to ask: what is this sentence about?
The main word that tells what a sentence is about is the simple subject.
When more than one subject share the same verb, you have a compound subject.
A subject together with all of its modifiers is the complete subject.