A quirk is an unusual habit, behavior, or characteristic that makes someone or something a little different in an interesting way. Everyone has quirks: maybe your best friend always organizes her pencils by color, or your uncle can't start his day without singing in the shower, or you have to touch every third fence post when you walk by.

Quirks aren't flaws or problems. They're the small peculiarities that make people unique and often endearing. A teacher might have the quirk of always wearing mismatched socks. A family dog might have the quirk of spinning in three circles before lying down. These behaviors seem odd to others but feel perfectly natural to whoever (or whatever) is doing them.

The word can also describe something unexpected in how objects work. An old house might have quirky doors that stick in humid weather, or a computer program might have a quirk that always opens to the wrong page first. Buildings, machines, and even systems can have quirks.

When you call something or someone quirky, you usually mean it affectionately. It suggests charm and individuality rather than weirdness. Scientists have their quirks, artists have their quirks, and your quirks are part of what makes you yourself.