Common Grammar Mistakes
The 25 most frequent errors in English — with examples and easy fixes
Commonly Confused Words
1. Their / There / They're
Their = possessive (their house). There = location (over there). They're = they are (they're coming). Test: if you can replace it with "they are," use they're.
2. Your / You're
Your = possessive (your book). You're = you are (you're welcome). Test: if you can replace it with "you are," use you're.
3. Its / It's
Its = possessive (the dog wagged its tail). It's = it is or it has (it's raining). This trips people up because possessives usually have apostrophes — "its" is the exception.
4. Effect / Affect
Affect is usually a verb (the weather affects my mood). Effect is usually a noun (the effect was dramatic). Memory trick: Affect = Action (both start with A), Effect = End result (both start with E).
5. Than / Then
Than = comparison (better than). Then = time/sequence (first this, then that).
6. Lose / Loose
Lose = to misplace or fail to win (don't lose your keys). Loose = not tight (the bolt is loose). One O = one outcome (lose). Two O's = two things not connected (loose).
Sentence Structure Errors
7. Run-On Sentences
Wrong: "I went to the store I bought milk." Right: "I went to the store. I bought milk." or "I went to the store and bought milk." Two independent clauses need a period, semicolon, or conjunction between them.
8. Comma Splices
Wrong: "I like coffee, she prefers tea." Right: "I like coffee, but she prefers tea." or "I like coffee; she prefers tea." A comma alone cannot join two complete sentences.
9. Subject-Verb Agreement
Wrong: "The list of items are on the desk." Right: "The list of items is on the desk." The subject is "list" (singular), not "items." Watch for phrases between the subject and verb that mislead you.
10. Dangling Modifiers
Wrong: "Walking to the store, the rain started." (The rain wasn't walking.) Right: "Walking to the store, I got caught in the rain." The modifier must be next to the thing it modifies.
11. Misplaced Modifiers
Wrong: "She almost drove her kids to school every day." (She almost drove but didn't?) Right: "She drove her kids to school almost every day." Place modifiers as close as possible to what they modify.
Punctuation Errors
12. Apostrophe Misuse
Apostrophes show possession (John's book) or contraction (don't = do not). They do NOT make plurals. "Apple's for sale" is wrong. "Apples for sale" is right. The 1990s, not the 1990's.
13. The Oxford Comma
"I love my parents, Batman and Wonder Woman" implies your parents are Batman and Wonder Woman. "I love my parents, Batman, and Wonder Woman" is clear. While the Oxford comma is technically optional, it prevents ambiguity and is required by most style guides (APA, Chicago).
14. Semicolons
Semicolons join two related complete sentences. "I love writing; it's my favorite hobby." Both sides must be able to stand alone as sentences. Don't use semicolons where a comma belongs.
15. Colon Misuse
Colons introduce lists, explanations, or elaborations. The clause before a colon must be a complete sentence. Wrong: "My favorites are: pizza, tacos, and sushi." Right: "I have three favorites: pizza, tacos, and sushi."
Word Usage Errors
16. Who / Whom
Who = subject (Who called?). Whom = object (Whom did you call?). Test: if you can answer with "he/she," use who. If you answer with "him/her," use whom.
17. Fewer / Less
Fewer = countable items (fewer apples). Less = uncountable quantities (less water). "10 items or fewer" is correct for the express lane, not "10 items or less."
18. Lay / Lie
Lay requires an object (lay the book down). Lie does not (lie down). Past tense makes it worse: lay → laid, lie → lay. "Yesterday I lay on the couch" is correct (past tense of lie).
19. Could Of → Could Have
"Could of" is always wrong. It comes from mishearing "could've" (could have). Same for would of (would have), should of (should have), might of (might have).
20. Literally
"I literally died laughing" — you didn't. Literally means actually, in reality. Using it for emphasis when you mean figuratively is technically incorrect, though increasingly accepted informally. In professional writing, use it only for its actual meaning.
Style & Clarity Issues
21. Passive Voice Overuse
Passive: "The ball was thrown by John." Active: "John threw the ball." Active voice is almost always clearer, shorter, and more engaging. Use passive voice deliberately (to emphasize the receiver of action or when the actor is unknown), not by default.
22. Nominalizations
"The investigation was conducted by the team" → "The team investigated." Turning verbs into nouns (investigate → investigation) bloats writing and obscures the actor. Strong verbs make strong writing.
23. Redundancy
"Past history," "free gift," "advance warning," "end result," "final conclusion," "brief summary," "completely unanimous," "close proximity." These phrases say the same thing twice. Cut the redundant word.
24. Starting with "There is/are"
"There are five reasons this matters" → "Five reasons make this matter" or simply "This matters for five reasons." "There is/are" almost always weakens the sentence opening.
25. Inconsistent Tense
Pick past or present tense and stick with it. "She walks to the store and bought milk" mixes present (walks) and past (bought). "She walked to the store and bought milk" is consistent.
Frequently Asked Questions
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