Hare and hair are homophones and easily confused words. The spell-check application of most word processing software programs would not catch a slip-up of these two words. Spell-check is looking for words that aren’t in its dictionary, and words that resemble words in its dictionary but are possibly spelled wrong. Spell-check isn’t perfect. It doesn’t know and can’t guess what word you wanted or what word you meant, it can only judge the words on the page. If you used words that are all spelled correctly, it gives you a pass anyway. Similarly, autocorrect on mobile phones might suggest one word instead of the other, it would be easy to do since both words start with “h-a.”
Hare is a noun, meaning a wild rodent that eats plants, know for it’s long ears, a fuzzy tuft tail, whiskers, and large hind legs that allow it to briskly jump across fields, deserts, and plains. Hares are larger than rabbits.
Hair is a noun, meaning the strands that grow out of the skin all over human bodies.
The following sentence uses both words correctly:
Harriett was so distraught that her domesticated hare had escaped, she pulled her own hair out.