Most writing mistakes are not rare or complicated. The same handful show up again and again in emails, essays and social posts. Learn these fifteen and you will avoid the majority of errors that make writing look careless.

Commonly confused words

1. Their, there and they’re

Their shows ownership, there is a place, and they’re means “they are”. Read the full guide.

Wrong: Their going home. Right: They’re going home.

2. Your and you’re

If you can replace it with “you are”, write you’re. Read the full guide.

Wrong: Your welcome. Right: You’re welcome.

3. Its and it’s

It’s always means “it is” or “it has”. Possessive its never takes an apostrophe. Read the full guide.

Wrong: The app updated it’s design. Right: The app updated its design.

4. Then and than

Use than for comparisons and then for time. Read the full guide.

Wrong: She is taller then me. Right: She is taller than me.

5. Affect and effect

Affect is usually the verb, effect the noun. Read the full guide.

Wrong: The rain effected the game. Right: The rain affected the game.

6. Lose and loose

Lose is the verb; loose means not tight. Read the full guide.

Wrong: Don’t loose your ticket. Right: Don’t lose your ticket.

Verb mistakes

7. Could of, should of, would of

After could, should, would, must and might, the word is always have. Read the full guide.

Wrong: I should of known. Right: I should have known.

8. Subject-verb agreement

Singular subjects take singular verbs: he goes, she has, it doesn’t.

Wrong: She don’t like coffee. Right: She doesn’t like coffee.

9. Plural subjects with was

Use were with they, we and you.

Wrong: They was late. Right: They were late.

10. Past tense after didn’t

After did, didn’t or did not, use the base verb.

Wrong: I didn’t went. Right: I didn’t go.

11. Shifting tenses

Pick one tense for a story and keep it. Time words like yesterday or last week need the past tense.

Wrong: Yesterday I go to the store and buy milk. Right: Yesterday I went to the store and bought milk.

Spelling and punctuation

12. A lot, not alot

“A lot” is always two words. Read the full guide.

Wrong: Thanks alot. Right: Thanks a lot.

13. Comma splices

Two complete sentences cannot be joined with only a comma. Use a period, a semicolon or a joining word.

Wrong: It was late, we went home. Right: It was late, so we went home.

14. Double negatives

Two negatives cancel each other out in standard English.

Wrong: I don’t need nothing. Right: I don’t need anything.

15. Fewer and less

Use fewer for things you can count and less for amounts.

Wrong: Less people came. Right: Fewer people came.

Catch them automatically

Nobody remembers every rule while they are writing. That is what a grammar checker is for. Paste your text into the free SpellMistake grammar checker and it flags every one of the mistakes above, explains why, and fixes them in one click.