The you (you)

Five tiny words cause most single-word errors: your/you're, their/there/they're, its/it's, affect/effect, and then/than.

Fast rules, many wrong/right pairs, workplace/school/casual examples, copyable rewrites and memory tricks help you fix sentences before you send them.

Short fix you can use now

Ask which meaning fits: possession, contraction (is/are/has), place/existence, comparison, influence/result, or time. Use the form that matches that meaning. When unsure, expand suspected contractions (you're → you are) or rewrite the clause to show possession clearly.

If you mean "you are," write you're; if something belongs to someone, write your.
Their = possession; there = place or existence; they're = they are (expand to check).
Affect = verb (action/ influence). Effect = noun (result).
Then = time/sequence. Than = comparison.

Core explanation: the five confusions in one line each

your vs. you're - your = possessive adjective (your report). you're = contraction of you are (you're ready). Expand to "you are" to test.

their / there / they're - their = possession (their keys). there = place or "there is/are" (put it there). they're = they are - expand to test.

its vs. it's - its = possessive (the dog licked its paw). it's = it is / it has (it's raining) - expand to test.

affect vs. effect - affect = verb (to influence). effect = noun (the result). Ask: action or result?

then vs. than - then = time/sequence; than = comparison. Ask: am I comparing two things?

Quick tests: expand contractions (you're → you are). Replace "there's" with "there is/are" to check meaning.
Possessive pronouns never take an apostrophe (its, yours, theirs).

Wrong: Your the project owner.
Right: You're the project owner.
Wrong: The company changed it's policy.
Right: The company changed its policy.

Examples: common wrong/right pairs

Read each wrong sentence, ask which meaning fits, then check the correct form.

Wrong: Your going to love this new feature.
Right: You're going to love this new feature.
Wrong: There report was filed late.
Right: Their report was filed late.
Wrong: It's warranty covers accidental damage.
Right: Its warranty covers accidental damage.
Wrong: The memo will effect hiring decisions.
Right: The memo will affect hiring decisions.
Wrong: I'll finish the task then you arrive.
Right: I'll finish the task when you arrive. (or) I'll finish the task before you arrive.
Wrong: I would rather stay then go out.
Right: I would rather stay than go out.
Wrong: They're car is in the shop.
Right: Their car is in the shop.

Work examples: emails, memos and reports

Small mistakes in professional writing look careless. Use these corrected sentences as quick fixes and prefer full forms in formal memos.

Work - Wrong: Please confirm your availability for the 3pm call.
Work - Right: Please confirm you're available for the 3pm call. (or) Please confirm your availability for the 3pm call.
Work - Wrong: There team completed the audit ahead of schedule.
Work - Right: Their team completed the audit ahead of schedule.
Work - Wrong: The system outage will effect invoice processing.
Work - Right: The system outage will affect invoice processing.
Work - Wrong: It's impact on Q4 revenue was larger than expected.
Work - Right: Its impact on Q4 revenue was larger than expected.

School examples: essays, lab reports and posts

Academic writing favors precision. Avoid contractions in formal essays and watch comparisons and possessives in technical descriptions.

School - Wrong: It's conclusion did not match the hypothesis.
School - Right: Its conclusion did not match the hypothesis.
School - Wrong: She scored higher then the class average.
School - Right: She scored higher than the class average.
School - Wrong: They're results were inconsistent across trials.
School - Right: Their results were inconsistent across trials.
School - Wrong: The treatment effected the control group.
School - Right: The treatment affected the control group.

Casual examples: texts, social posts and chats

Casual messages are fast and full of contractions. Small edits keep meaning clear without changing tone.

Casual - Wrong: Your coming to the party, right?
Casual - Right: You're coming to the party, right?
Casual - Wrong: I can't believe it's over already - that show had great its effects.
Casual - Right: I can't believe it's over already - that show had great effects.
Casual - Wrong: Do you know if there tickets are still available?
Casual - Right: Do you know if their tickets are still available?
Casual - Wrong: I'll see you then, you're the best!
Casual - Right: I'll see you then - you're the best!

Try your own sentence

Test the whole sentence instead of the phrase alone - context usually makes the correct form obvious.

Rewrite help: fix a sentence step by step

Three quick steps: 1) Spot the suspect word. 2) Decide the needed meaning (possession, contraction, place, comparison, influence/result, or time). 3) Replace the word and read it aloud. If both forms seem plausible, rewrite to remove ambiguity.

If two forms seem possible, make the relationship explicit (e.g., change "your team" to "the team's X").

Rewrite:
Original: I think its going to rain, could effect our plans.
Rewrite: I think it's going to rain, which could affect our plans.
Rewrite:
Original: Your the only one than can approve this.
Rewrite: You're the only person who can approve this.
Rewrite:
Original: There fewer options then expected.
Rewrite: There are fewer options than expected.
Rewrite:
Original: It's effect on sales was clear.
Rewrite: Its effect on sales was clear. Or: The change clearly affected sales.

Memory tricks that actually work

Fast mental shortcuts you can run in seconds before sending a message.

Contraction expansion: if you can expand to "you are," "they are," or "it is/has," use the contraction.
Affect = Action (both start with A). Effect = End/result (E for end).
Your = belongs to you. There = place/existence. Their = belongs to them.
Then = time/sequence. Than = comparison.

Punctuation, hyphenation and spacing notes

Apostrophes mark contractions and possessive nouns (company's) but not possessive pronouns (its, yours, theirs). It's always means "it is" or "it has."

Hyphens appear in compound adjectives before a noun (long-term effect). Omitting the hyphen can create ambiguity.

Spacing: do not add spaces inside contractions or possessives (it's, don't). Extra spaces can hide errors from spellcheck.

Never use it's for possession.
Correct: long-term effect. Less clear: long term effect.
Bad spacing: It ' s ready. Good: It's ready.

Similar mistakes to add to your checklist

These follow the same pattern: similar sound or spelling, different roles. Add them to your quick find-before-sending list.

Loose vs. lose - loose (not tight), lose (misplace).
Accept vs. except - accept (receive), except (excluding).
Who vs. whom - who = subject, whom = object (use "him/her" test).
Lay vs. lie - lay requires a direct object; lie does not.
Fewer vs. less - fewer for countable items, less for uncountable amounts.

Usage: Wrong: There are less people than last year.
Right: There are fewer people than last year.

FAQ

How can I quickly remember your vs you're?

Expand you're to "you are." If the sentence still makes sense, use you're; otherwise use your for possession.

When do I use its vs it's in formal writing?

Use its for possession. It's only means "it is" or "it has." Prefer the full form ("it is") in formal writing to avoid contractions.

What's a fast test for affect vs effect?

Ask: do I need a verb (action) or a noun (result)? If action → affect. If result → effect. If unsure, rewrite the sentence to use a clearer verb or noun.

Are grammar checkers reliable for these errors?

Most checkers catch many mistakes, but they may mis-suggest in unusual contexts. Use the meaning tests here when a suggestion feels wrong.

Any quick proofreading checklist before I send an email?

Scan for your/you're, their/there/they're, its/it's, affect/effect and then/than. Expand contractions mentally and read the sentence aloud to confirm meaning.

Need a second pair of eyes?

If you still hesitate, paste the sentence into a grammar checker for suggestions and then run the quick meaning checks here. Combining both approaches finds most errors quickly.