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Two short tokens, one apostrophe - big difference. Use its for possession (belongs to it); use it's only as a contraction of it is or it has.

Quick checks, plenty of wrong/right pairs, copy-ready rewrites for emails and reports, workplace/school/casual examples, a memory trick, and related pitfalls to watch for.

Quick answer

Use its (no apostrophe) for possession. Use it's (with apostrophe) only when you mean it is or it has.

Its = possessive (The cat groomed its paw).
It's = contraction (It's late; it's been fixed).
Proof: try replacing with "it is" or "it has." If that makes sense, use it's; if not, use its.

Core explanation: possession vs contraction

Its is a possessive determiner (like his, her, their). It's is a contraction where the apostrophe replaces missing letters in it is or it has.

Possessive: its + noun - its tail, its color, its policy.
Contraction: it's = it is / it has - It's cold. It's been updated.
Wrong: The dog wagged it's tail.
Right: The dog wagged its tail.

Three fast checks while proofreading

Run these in order; each takes seconds and catches most errors.

Read the sentence aloud. Does "it is" or "it has" fit? If yes → it's.
Ask ownership: does something belong to it? If yes → its.
When in doubt, expand the phrase into the full sentence: context usually makes the choice clear.

Wrong: The company updated it's privacy policy yesterday.
Right: The company updated its privacy policy yesterday.

Real usage and tone

Possessive its is neutral and always correct when indicating ownership. It's (contraction) fits casual writing, dialogue, and many emails; avoid contractions in formal reports and academic prose where you can write it is or it has in full.

Formal (work): The device performed within its specified parameters.
Casual: It's been a long week - let's catch up Saturday.
School: Its scope includes both qualitative and quantitative results.

Examples: wrong/right pairs across contexts

Practical wrong/right pairs for emails, reports, assignments, and texts. Read the wrong sentence, then the corrected version.

Wrong: The website clarified it's terms of service.
Right: The website clarified its terms of service.
Wrong: The robot lost it's balance after the update.
Right: The robot lost its balance after the update.
Wrong: The committee postponed it's vote until Monday.
Right: The committee postponed its vote until Monday.
Wrong: The bird cleaned it's feathers in the morning.
Right: The bird cleaned its feathers in the morning.
Wrong: The printer finished it's job and shut down.
Right: The printer finished its job and shut down.
Wrong: The lab turned in it's results late.
Right: The lab turned in its results late.
Wrong: My phone kept reminding me because it's battery was low.
Right: My phone kept reminding me because its battery was low.
Wrong: The report includes it's summary on page 5.
Right: The report includes its summary on page 5.
Wrong: Its a shame we missed the deadline.
Right: It's a shame we missed the deadline.
Wrong: It's sensors failed during the test.
Right: Its sensors failed during the test.
Wrong: The website, because it's design is new, looks modern.
Right: The website, because its design is new, looks modern.
Wrong: Their going to post it's findings tomorrow.
Right: They're going to post its findings tomorrow.

Rewrite help: step-by-step fixes you can paste in

Three quick steps: 1) Read it aloud. 2) Replace the suspect word with "it is" or "it has." 3) Choose its or it's and adjust punctuation.

Keep tone: expand contractions for formal writing; keep them in informal messages.
Rewrite:
Original: The dog wagged it's tail. → The dog wagged its tail.
Rewrite:
Original: It's sensors failed during the test. → Its sensors failed during the test.
Rewrite:
Original: Its a shame we missed the deadline. → It's a shame we missed the deadline.

Try your own sentence

Test the entire sentence, not just the word. Context usually makes the correct form obvious.

Memory trick that actually works

Apostrophes stand in for missing letters. Possession doesn't drop letters, so no apostrophe for its. If you can say "it is" or "it has," then use it's.

Ask aloud: "Can I say it is?" If yes → it's. If no → its.
Visual trick: picture its as a label stuck on an object (its tail, its color) - no missing letters, no apostrophe.
Quick: It's = it is → It's raining. Its = possessive → The company changed its logo.

Spacing, hyphenation and punctuation: fine-print that matters

No spaces around apostrophes (write it's, not it ' s). Hyphenation doesn't affect whether to use its or it's. The possessive its never takes an apostrophe, even before punctuation.

Apostrophes do not form plurals - write 1990s, CDs, bosses.

Wrong: Its' handlebars were scratched.
Right: Its handlebars were scratched.
Wrong: 1990's trends.
Right: 1990s trends.

Similar mistakes to watch for

These errors are easy to miss. Use parallel swaps: expand contractions or ask who owns what.

your vs you're - your = possession, you're = you are.
their vs they're vs there - their = possession, they're = they are, there = place.
Don't use apostrophes for plurals - apples, CDs, 2020s.
Wrong: Your going to love its new layout.
Right: You're going to love its new layout.

Quick practice: a 30-second checklist

Run this checklist on every short email or post that contains it, its, it's, your, you're, or their/there/they're.

1) Read the sentence aloud.
2) Expand the suspect word to "it is" / "it has" / "you are." If it works, use the contraction form.
3) If the word indicates ownership, use the possessive form with no apostrophe (its, your, their).
4) Re-scan punctuation and spacing (no spaces around apostrophes).

Practice: Its been two days since we heard back. → It's been two days since we heard back.
Practice: The device rebooted itself because it's software had a bug. → The device rebooted itself because its software had a bug.
Practice: Their going to post the update on it's page. → They're going to post the update on its page.

FAQ

Is it ever correct to write it's for possession?

No. It's is only a contraction for it is or it has. Possessive its never takes an apostrophe.

What's the fastest way to check its vs it's in an email?

Replace the word with "it is" or "it has." If the sentence still makes sense, use it's; if not, use its. Reading the sentence aloud helps.

Can I use contractions in formal writing?

Avoid contractions in formal reports and academic prose. Write it is or it has in full for a formal tone.

When should I use an apostrophe for plurals (like 1990's)?

Most style guides recommend no apostrophe for plurals of years or acronyms (1990s, CDs). Use apostrophes only for possession or contractions.

Will grammar checkers always catch these mistakes?

Grammar checkers catch many its/it's errors but can be wrong in ambiguous contexts. Use the expansion test and your judgment for best results.

Want a quick second opinion?

If you're unsure, run the expansion test above or paste the sentence into a checker. Fix three sentences from your last draft using the rewrites here - it's a fast way to turn awareness into accuracy.