you're
Shortening of two
You're is the contraction of "you are": You're late, You're not going to believe this.
It's frequently confused with the possessive "your" in writing, though the words sound identical.
You're welcome is the standard response to thanks.
they're
Contracted third-person plural
she's · it's · isn't · aren't · wasn't · weren't · that's · what's · who's · here's
- homophoneshomophones, hear, here, see, sea
- you're welcomePolite reply to gratitude
- you're kiddingExpression of surprised disbelief
- you're fineDismissive comfort phrase
- you're firedTermination of employment announcement
- you're okayReassurance of wellbeing
- you're safeReassurance of protection