A chalazion is a bump that can be found on the eyelids. Whereas a stye is often painful, a chalazion is usually free from pain and has a rubbery feel about it. Another difference is that whereas a stye is caused by a bacterial infection, a chalazion is caused by a buildup of fluid due to a blockage, or by the fluids within being thicker than usual.
A chalazion will usually drain away itself within a few days or so without having done any harm. They can sometimes last longer, though, in which case you should arrange to speak with a doctor.
If they are a regular occurrence then you should try to get them checked out to see if there is an underlying problem causing them.
Cause #1: Seborrheic Dermatitis
Our skin is naturally quite oily. We will often try to wash this away, but it is not healthy for our skin to do away with it completely. The oil helps to keep our skin soft and supple, protecting it against cracking and other damage. The oily waxes are secreted from the seborrheic glands, which are found all over the skin.
Seborrheic dermatitis is a condition that causes the skin to become red and inflamed, along with other symptoms. It is caused by a type of yeast that thrives on the oils secreted by the skin. In addition to the redness and inflammation it causes, it can also lead to the formation of a chalazion.