With the assistance of our friends from Stargate: SG1.
Let's start with their, which indicates possession. For example:
While the Goa'uld ruling the planet were fighting the rest of SG1, Vala couldn't resist helping herself to their collected treasures.While their indicates possession, they're is a contraction of "they are" or "they were". If you can substitute either "they are" or "they were" in your sentence, you definitely should use they're.
Daniel's expression was incredulous as he looked at the bulging backpack Vala was struggling to carry.Our last homophone is there, which is an adverb indicating a location, real or imagined, and can also be used as an exclamation.
"They're just a few trinkets I picked up along the way," Vala said sweetly.
"How could you make me leave everything there!" Vala demanded of Daniel.While all these words sound similar, it's very important to make sure you're using them in the right context because they are very easy to confuse. Test them out, read them over, and make sure your beta knows the difference. ;^)
"It was either that or leave you behind," exclaimed Daniel, exasperated as usual with her behavior.