Same sound, different word: traps even native writers fall into
their - there - they're
How to use this sheet
These mix-ups are not learner errors - they are the slips of fluent people writing at speed, because each set sounds identical or nearly so while the spellings do different jobs. The reliable test is substitution: expand the apostrophe form into its full two words and see whether the sentence still works; if it does not, you needed the possessive spelling. Spell-checkers miss most of these, because every wrong choice is still a real word.
| Confusion set | How to tell them apart | Example |
|---|---|---|
| its / it's | possessive; contraction of pronoun + verb | The team changed its name - it's shorter now. |
| their / there / they're | possessive; place; contraction of pronoun + verb | They're selling their house over there. |
| your / you're | possessive; contraction of pronoun + verb | You're welcome to bring your dog. |
| whose / who's | possessive; contraction of pronoun + verb | Who's the neighbour whose alarm kept ringing? |
| affect / effect | verb meaning to influence; noun meaning a result | The strike didn't affect flights, and its effect on trains was small. |
| lose / loose | verb meaning to misplace or be beaten; adjective meaning not tight | Tighten that loose screw or you'll lose it. |
| then / than | time or sequence; comparison | Back then, the trip cost less than it does now. |
| to / too | direction, or part of a verb form; excessively, or also | It's too far to walk. |
| should have / should of | only the first exists; the second is fast speech written down | You should have seen his face. |
In use
It's been years since the band changed its sound. They're convinced their flight leaves from there. Who's going to tell her whose fault it really was?
Watch out
Your going to love it here.
In the pronoun sets, the apostrophe never marks possession - the exact opposite of the rule for ordinary nouns, which is why even careful writers slip. Whenever you type an apostrophe form, say the two full words aloud in its place: if the sentence survives, the apostrophe is right; if not, you wanted the possessive twin. Row 9 is not a real alternative at all - the second spelling is simply an error, however often you see it online.