Your or you're

Your” shows possession. Try replacing “your” with “my” in a sentence. If it works, then use “your”.

Example: “Is this your office?” (This means: Does this office belong to you?)

You’re” is a contraction or combination of “you are”.

Example: “Please phone me when you’re in Cologne”. (This means: Please phone me when you are in Cologne.)

Don’t worry too much. Even native speakers get this wrong! 😉