Three words, three jobs
"Their," "there," and "they're" sound identical but serve completely different grammatical roles. "Their" is a possessive pronoun showing ownership. "There" indicates a place or introduces the existence of something. "They're" is a contraction of "they are." Confusing these three is arguably the most common homophone error in English.
Because spell-checkers will not catch the mistake (all three are valid words), you need a mental checklist to get them right every time.
When to use each form
Each word has a clear function. Once you learn to test for that function, the correct spelling becomes obvious.
- "Their" shows possession: Their project deadline is Friday. Their car is parked outside.
- "There" refers to a place or introduces existence: The report is over there. There are three options to consider.
- "They're" is always expandable to "they are": They're planning to launch next month. They're the best candidates we interviewed.
The substitution test
Try expanding the word to "they are." If the sentence still makes sense, write "they're." If you can replace the word with "our" or "his" and the sentence works, write "their." If neither substitution works, write "there."
This three-step test takes seconds and catches virtually every error. Run it during editing, and these mistakes will disappear from your writing.
Common pitfalls
Autocorrect and voice-to-text tools frequently choose the wrong form. "Their going to be late" is a classic autocorrect error. Another trap is possessive phrases like "their own," which some writers mistakenly spell as "there own." When editing, search your document for all three spellings and verify each one individually.