Epistaxis, commonly known as a nosebleed, occurs when nasal blood vessels bleed due to damage or trauma. There are two main types of epistaxis: anterior, which involves the nasal septum and is more common but less severe; and posterior, which involves deeper blood vessels and is less common but more severe and difficult to control. Epistaxis can be caused by nose picking, trauma, or underlying medical issues. Treatment focuses on controlling bleeding through methods like applying pressure, cauterization, or nasal packing depending on the severity.