Grammar Basics
Grammar is the set of rules that govern how words work together in a language. Understanding grammar helps you write clearly, speak confidently, and avoid the errors that can distract readers from your ideas. This guide covers the foundations: the eight parts of speech, how sentences are built, the most common mistakes students make, and the difference between active and passive voice.
The 8 Parts of Speech
Every word in the English language belongs to a category called a part of speech. Each category describes what the word does in a sentence. The same word can sometimes belong to different categories depending on how it is used.
| Part of Speech | What It Does | Example Words | Example in a Sentence |
|---|---|---|---|
| Noun | Names a person, place, thing, or idea | dog, city, freedom, Maria | The dog ran across the park. |
| Pronoun | Replaces a noun to avoid repetition | he, she, it, they, we, I, you | Maria was tired, so she went to bed. |
| Verb | Shows action or a state of being | run, think, is, was, become | The students studied for hours. |
| Adjective | Describes or modifies a noun or pronoun | tall, blue, three, happy | She wore a bright red jacket. |
| Adverb | Modifies a verb, adjective, or another adverb | quickly, very, well, never | He spoke very quietly. |
| Preposition | Shows relationship between a noun and other words | in, on, under, between, after | The book is on the table. |
| Conjunction | Connects words, phrases, or clauses | and, but, or, because, although | I was tired, but I finished the assignment. |
| Interjection | Expresses emotion; stands apart from the sentence | Wow, Oh, Hey, Ouch, Well | Wow, that was an incredible performance! |
A Closer Look at Each Part of Speech
Nouns
Nouns fall into several sub-types. Common nouns name general things (book, city, teacher). Proper nouns name specific things and are always capitalized (London, Ms. Johnson, Monday). Collective nouns name groups (team, flock, family). Abstract nouns name ideas you cannot physically touch (love, courage, justice).
Pronouns
Pronouns must agree with the noun they replace in gender and number. Common problems arise when writers use a plural pronoun (they) for a singular noun (the student). "Each student must turn in their essay" is now widely accepted, but knowing the traditional rule (his or her) helps in formal writing contexts.
Verbs
Verbs show action (she runs, he built, they decided) or state of being (he is, she was, they seem). Linking verbs connect the subject to a description: "The soup smells wonderful." Helping verbs (auxiliary verbs) work with main verbs to form tenses: "She has finished" or "They will arrive."
Adjectives
Adjectives answer the questions: Which one? What kind? How many? They typically come before the noun they modify (the tall building) or after a linking verb (the building is tall). Articles (a, an, the) are a special type of adjective.
Adverbs
Adverbs answer: How? When? Where? To what degree? Many adverbs end in -ly (slowly, carefully, loudly), but not all do (fast, well, very, quite). Importantly, the word "fast" is both an adjective and an adverb depending on use: "a fast car" (adjective) vs. "she ran fast" (adverb).
Subject and Predicate
Every complete sentence has two parts: the subject and the predicate.
- The subject is what or who the sentence is about. It always contains a noun or pronoun.
- The predicate tells what the subject does or is. It always contains a verb.
| Subject | Predicate |
|---|---|
| The old cat | slept by the fireplace all afternoon. |
| All three students in the front row | passed the exam with high marks. |
| Running every morning | improves your focus. |
Types of Sentences
Sentences are classified by the number and type of clauses they contain. A clause is a group of words with its own subject and verb. An independent clause can stand alone as a sentence. A dependent clause cannot stand alone — it needs an independent clause to make complete sense.
| Sentence Type | Structure | Example |
|---|---|---|
| Simple | One independent clause | The dog barked. |
| Compound | Two or more independent clauses joined by a conjunction or semicolon | The dog barked, and the cat ran away. |
| Complex | One independent clause + one or more dependent clauses | The dog barked because it heard a noise. |
| Compound-Complex | Two or more independent clauses + one or more dependent clauses | The dog barked because it heard a noise, and the cat hid under the bed. |
Common Grammar Mistakes
1. Subject-Verb Agreement
A verb must agree with its subject in number. Singular subjects take singular verbs; plural subjects take plural verbs. The tricky part is identifying the true subject when other words come between the subject and the verb.
| Incorrect | Correct |
|---|---|
| The list of items were long. | The list of items was long. (subject = "list," singular) |
| Each of the students have a pencil. | Each of the students has a pencil. ("each" is singular) |
| Neither the teacher nor the students was ready. | Neither the teacher nor the students were ready. (verb agrees with nearer subject) |
2. Run-On Sentences
A run-on sentence incorrectly joins two or more independent clauses without proper punctuation or a conjunction. There are three main ways to fix one.
Run-on: I stayed up late studying I was exhausted the next morning.
Fix 1 (period): I stayed up late studying. I was exhausted the next morning.
Fix 2 (semicolon): I stayed up late studying; I was exhausted the next morning.
Fix 3 (conjunction): I stayed up late studying, so I was exhausted the next morning.
3. Sentence Fragments
A fragment is an incomplete sentence. It is missing either a subject, a verb, or it is a dependent clause trying to stand alone.
| Fragment | Why It Fails | Fixed |
|---|---|---|
| Running down the street. | No subject | She was running down the street. |
| The reason being lack of sleep. | No complete verb | The reason was lack of sleep. |
| Because I was late. | Dependent clause alone | I missed the beginning because I was late. |
4. Dangling Modifiers
A dangling modifier is a phrase that is meant to describe something, but the thing it describes is not clearly stated in the sentence. The modifier is left "dangling" without a logical subject to attach to.
Dangling: Walking through the park, the flowers were beautiful.
(Who was walking? Not the flowers.)
Fixed: Walking through the park, she noticed that the flowers were beautiful.
Dangling: Having finished the exam, the classroom was quiet.
Fixed: Having finished the exam, the students found the classroom quiet.
Active vs. Passive Voice
Voice tells you whether the subject of the sentence is doing the action (active) or receiving the action (passive).
- Active voice: Subject → Verb → Object. The subject performs the action.
- Passive voice: The subject receives the action. Formed with a form of "to be" + past participle.
| Active Voice | Passive Voice |
|---|---|
| The chef cooked the meal. | The meal was cooked by the chef. |
| The committee approved the budget. | The budget was approved by the committee. |
| Scientists discovered a new species. | A new species was discovered by scientists. |
Active voice is generally preferred because it is more direct, uses fewer words, and is easier to read. Passive voice is useful when the doer of the action is unknown, unimportant, or when you want to emphasize the thing being acted upon rather than who did it. Example: "The ancient coins were discovered in 1987" (passive, because we may not know who found them).
Frequently Asked Questions
What is the difference between a phrase and a clause?
A phrase is a group of related words that does not contain both a subject and a verb. It functions as a single part of speech within a sentence. Examples: "in the morning" (prepositional phrase), "running quickly" (participial phrase). A clause is a group of words that does contain both a subject and a verb. An independent clause is a complete thought that stands alone as a sentence. A dependent clause has a subject and verb but cannot stand alone because it begins with a subordinating word like "because," "although," "when," or "if."
When should I use "who" versus "whom"?
Use "who" when it refers to the subject of the clause (the one doing the action). Use "whom" when it refers to the object (the one receiving the action). A helpful trick: substitute "he/she" or "him/her" in the sentence. If "he" or "she" sounds right, use "who." If "him" or "her" sounds right, use "whom." Example: "Who called?" (He called — use "who.") "To whom should I send this?" (Send it to him — use "whom.")
Is it ever acceptable to end a sentence with a preposition?
Yes. The rule against ending sentences with prepositions is a prescriptive rule invented by 18th-century grammarians who wanted English to follow Latin grammar. In modern usage, ending a sentence with a preposition is widely accepted, especially when avoiding it creates an awkward or overly formal sentence. "That is the rule I was thinking about" is more natural than "That is the rule about which I was thinking." That said, formal academic writing may still discourage the practice, so know your audience.
What is the difference between a coordinating and a subordinating conjunction?
A coordinating conjunction joins elements of equal grammatical rank — two independent clauses, two nouns, two adjectives, etc. There are seven coordinating conjunctions, remembered with the acronym FANBOYS: For, And, Nor, But, Or, Yet, So. A subordinating conjunction introduces a dependent clause and shows how it relates to the main clause. Common subordinating conjunctions include because, although, when, if, since, while, unless, and after. "She studied hard, but she still felt nervous" (coordinating). "She still felt nervous although she had studied hard" (subordinating).
Quick Quiz
Check your understanding. Click an answer to see if you got it right.