One of the more curious aspects of English is the use of "homonyms" and "homophones" within the vocabulary. "Homonyms" and "homophones" share a common condition: and two (or three) words sound the same yet mean something wholly different from each other. The difference is this: "homoyms" are spelled the same while "homophones" are spelled differently.
Thus, "technically", "there" and "their"