Hadiths in Islam
What is a Hadith?
Hadiths are oral beliefs, customs or practices relating to the words and deeds of the prophet Muhammad (S.A.W). Hadith collections are regarded by all traditional schools of jurisprudence as important tools for determining the Muslim way of life and Prophet Muhammad's (S.A.W) sunnah.
According to some scholars, Hadith means "what was transmitted on the authority of the Prophet, his deeds, sayings, tacit approval, or description of his features". They say that a hadith is a narration about the life of the Prophet or what he approved - as opposed to his life itself, which is the Sunnah.
Ultimately, Hadiths are mostly the word of Muhammad (S.A.W) and not the word of Allah, like the Qur'an is. The 2 most reliable Hadiths out of the many collections are Sahih Bukhari and Sahih Muslim. Other notable collectors are Abu Da'ud and Al Tirmidhi.
References:
[1] http://en.wikipedia.org/wiki/Hadith
[2] http://www.nicheoftruth.org/pages/sunnah.htm