What is a stye in the eye?

Infection: A stye is a bacterial infection of an oil-producing gland at the edge of the eyelid.

Clogged oil gland.: A stye is a clogged oil gland found in the eyelid margin, it produces oil for the surface of the eye. When the orifice of this gland becomes blocked, the oil will back up and form what is called a stye. Typically a stye is from inflammation causing the opening (orifice) to occlude causing the stye. A stye is typically not an infected oil gland, but can occur due bacteria causing inflammation.