Spelling Mistakes vs. the Spelling Checker

You might think your spelling is perfect because you've run the spelling checker. Remember, though, that spelling checker programs don't find homonyms (using "their" when you mean "there," for example). They also don't recognize most proper names, so be sure to check the names of people, places, and organizations. So don't count on your computer to save you from the dirty work of proofreading. Spelling checkers are getting smarter, but there is still no substitute for a human proofreader.