A tic is a sudden, quick movement or sound that a person makes without meaning to. Tics can be physical, like rapidly blinking your eyes, jerking your head to one side, or shrugging your shoulders. They can also be vocal, like repeatedly clearing your throat, sniffing, or making small clicking noises.

Tics are different from deliberately doing something: they happen automatically, like a sneeze or a hiccup. Some people have occasional tics that come and go, especially when they feel stressed or tired. Others have tics that happen more frequently as part of a condition. Either way, tics are involuntary, which means the person isn't choosing to do them and often can't easily stop them.

Many kids experience temporary tics at some point, which usually fade away on their own. People are generally encouraged not to make a big deal about someone else's tic, because pointing it out or asking them to stop can increase stress and make the tic happen even more.