Here's a quick and easy guide to the most commonly misspelled or misused three words: Their - used to indicate possession ONLY - as in something is part of or owns something. ie. Tesla is a great company. Their employees must be loving their stock options! They're - contraction of "they are". Tesla has great employees. They're on a roll right now. There - use for everything else. There are about 4,000 employees that work over there.