Conjunctivitis, also known as pinkeye, is an inflammation of the conjunctiva that is usually caused by allergy, infection, or trauma. It causes redness, itching, burning eyes, swelling, and discharge. Treatment involves administering antibiotic or antiviral eye drops as prescribed, keeping the infected person home from school until antibiotics have been used for 24 hours, and instructing on infection control measures like handwashing to prevent spread.