A sebaceous cyst is a small, non-cancerous lump that forms beneath the skin. It occurs when a hair follicle or skin pore becomes blocked, leading to the accumulation of sebum, a natural oil produced by the skin. These cysts can appear anywhere on the body but are most commonly found on the face, neck, and torso. Typically, sebaceous cysts are painless and may vary in size. They can sometimes become inflamed or infected, leading to discomfort. While they are generally harmless, treatment options include drainage or surgical removal if they cause issues or for cosmetic reasons.