A stye is an inflammation (often painful) caused by the infection of the meibomian gland near the eyelash follicles. The stye is typically on the edge of the eyelid, is red and quite painful. The first line of treatment for a stye is to repeatedly apply a hot moist washcloth (with a touch of baby shampoo) for a few days, and patients should note that the this treatment may increase the swelling for a few days before it begins to alleviate. Antibiotics may be necessary if it does not dissipate, or the surgeon may elect to incise and drain the stye.
The animation below provides a description of a stye.