A tic is a sudden, involuntary movement or sound that occurs repeatedly. It can be a twitching of the face or neck muscles, an eye blink, a grimace, or even a vocalization such as a cough or clicking noise. Tics are often seen in children and teenagers with conditions like Tourette syndrome or chronic motor tic disorder. They can be caused by various factors including genetics, environmental triggers, and neurochemical imbalances. While most people outgrow their tics as they get older, some may continue to experience them into adulthood.