Conjunctivitis can be divided into two categories, infectious and non-infectious, depending on the nature of the inflammation. Infectious conjunctivitis is an inflammation of the conjunctiva due to infection by pathogenic microorganisms, which may be bacteria, viruses, chlamydia, fungi, etc. Signs of infectious conjunctivitis are important in distinguishing between different types of conjunctivitis, such as copious purulent discharge seen in gonococcal conjunctivitis, mucopurulent discharge seen in bacterial and chlamydial conjunctivitis, and watery discharge seen in viral conjunctivitis, which is also often associated with subconjunctival hemorrhage and enlarged preauricular lymph nodes. Treatment is usually based on clinical manifestations and signs, a preliminary judgment of the type of conjunctivitis, empirical treatment, and if treatment is not effective, conjunctival scraping and bacterial culture of conjunctival secretions may be performed to confirm the diagnosis of which pathogenic microbial infection is present and targeted treatment. The main route of transmission of infectious conjunctivitis is by contact, so attention to hand hygiene is most important for the prevention of conjunctivitis. The etiology of non-infectious conjunctivitis is varied, most commonly caused by local or systemic allergic reactions, sunlight, biotoxins, and various chemicals can also cause non-infectious conjunctivitis. It is important to note that refractive error (when glasses are required) is also a common cause of non-infectious conjunctivitis. Therefore, enhancing physical fitness, proper eye care, and avoiding exposure to allergens are effective ways to reduce the occurrence of noninfectious conjunctivitis.