Hadith in Islam refers to the collected traditions, sayings, actions, and approvals of the Prophet Muhammad. These records are considered a primary source of guidance for Muslims, second only to the Quran. Hadiths help explain and interpret the Quranic verses, providing context and detailed practices for various aspects of Islamic life. They are categorized based on their authenticity, with classifications such as Sahih (authentic), Hasan (good), and Da'if (weak). Major collections include those compiled by scholars like Bukhari, Muslim, and Tirmidhi. The study and understanding of hadith are central to Islamic jurisprudence and theology.