A chalazion is a small painless bump on the eyelid. It happens when the eyelids oil glands clog up. It could start as an internal hordeolum (Stye). It could affect the upper or the lower lid.
The contents of a chalazion include pus and blocked fatty secretions that normally help in lubrication of the eye, but are blocked out.
Many times the chalazion drain out and resolve on their own. Frequent warm compresses on the eyelid also help to liquify the secretions and prevent clogging of the pores.
In case they don't resolve on their own and persist for several weeks causing cosmetic problems, your eye doctor can surgically excise it out too. It is a simple procedure, where a small cut is made in the center of the chalazion, and he squeezes the blocked contents out of the incisions.
VissionTip : Incase you are getting multiple chalazions and styes, do visit your doctor! There could be a possibility that you have a refractive error.