Conjunctivitis, commonly known as pink eye, is an inflammation or infection of the transparent membrane lining the eyelid and eyeball that causes the eye to appear pink or red. There are two main types of conjunctivitis - infectious and non-infectious. Infectious conjunctivitis can be bacterial or viral, with bacterial conjunctivitis more common in children. Common symptoms include redness, discharge, and eye irritation or stickiness. Treatment depends on the cause but may include antibiotic or antihistamine eye drops. Proper hygiene and not sharing personal items can help prevent the spread of infectious conjunctivitis.