Common Grammar Mistakes

The Most Frequent English Errors and How to Fix Them

Even experienced writers make these common mistakes. Learning to recognize them will dramatically improve your writing. Our free grammar checker can catch most of these automatically.

Commonly Confused Words

Want detailed rules? Start with Its vs It's, Your vs You're, and Their vs There vs They're.

Its vs. It's

❌ Wrong:

"The dog wagged it's tail."

✓ Correct:

"The dog wagged its tail."

Rule: "It's" always means "it is" or "it has." "Its" is possessive (showing ownership). If you can replace it with "it is," use "it's."

Your vs. You're

❌ Wrong:

"Your going to love this."

✓ Correct:

"You're going to love this."

Rule: "You're" means "you are." "Your" shows possession. Test by expanding to "you are"—if it makes sense, use "you're."

Their, There, They're

❌ Wrong:

"Their going to there house."

✓ Correct:

"They're going to their house."

Rules:
  • Their = possessive (their house, their car)
  • There = location (over there, there is)
  • They're = they are (they're coming)

Then vs. Than

❌ Wrong:

"This is better then I expected."

✓ Correct:

"This is better than I expected."

Rule: "Than" is for comparisons (bigger than, better than). "Then" is for time sequences (first this, then that).

Affect vs. Effect

❌ Wrong:

"The rain will effect the game."

✓ Correct:

"The rain will affect the game."

Rule: "Affect" is usually a verb (to influence). "Effect" is usually a noun (the result). Remember: Affect = Action, Effect = End result.

Lose vs. Loose

❌ Wrong:

"Don't loose your keys."

✓ Correct:

"Don't lose your keys."

Rule: "Lose" (one O) = to misplace or fail to win. "Loose" (two O's) = not tight. Think: "Loose" has room for two O's because it's not tight!

Punctuation Mistakes

For full punctuation lessons, see Comma Rules, Semicolon Usage, and Apostrophe Rules.

Comma Splices

❌ Wrong:

"I love writing, it's my passion."

✓ Correct:

"I love writing. It's my passion."

"I love writing; it's my passion."

"I love writing—it's my passion."

Rule: Don't join two complete sentences with just a comma. Use a period, semicolon, or em dash instead.

Apostrophe in Plurals

❌ Wrong:

"I bought three apple's."

✓ Correct:

"I bought three apples."

Rule: Apostrophes show possession or contractions, NOT plurals. Just add "s" or "es" for plurals.

Grammar Mistakes

Practice these patterns with Subject-Verb Agreement, Who vs Whom, and Tense Consistency.

Subject-Verb Agreement

❌ Wrong:

"The team are playing well."

✓ Correct:

"The team is playing well."

Rule: Collective nouns (team, family, group) are usually singular in American English. The verb should match.

Who vs. Whom

❌ Wrong:

"Who did you give it to?"

✓ Correct:

"Whom did you give it to?"

"To whom did you give it?"

Rule: Use "who" for subjects (who did this?) and "whom" for objects (to whom?). Tip: If you can answer with "him," use "whom" (both end in M).

Check Your Writing Automatically

Our free grammar checker catches these mistakes and many more—instantly.

Try Grammar Checker Free