Sunnah

The term Sunnah comes from the root word sanna, which means to pave the way or make a path easily passable, such that it becomes a commonly followed way by everyone afterwards. Thus sunnah can be used to describe a street or road or path on which people, animals, and cars travel. Additionally, it can apply to a prophetic way, i.e. the law that they brought and taught as an explanation or further clarification of a divinely revealed book. Normally, the prophetic way includes references to his sayings, actions, physical features and character traits.
From the Islamic standpoint, Sunnah refers to anything narrated or related about the Prophet Muhammad (pbuh), authentically traced to him regarding his speech, actions, traits, and silent approvals, before and after the revelation.
Each narration is composed of two parts: the isnad and the matn. The isnad refers to a chain of people who narrated a paricular narration. The matn is the actual text of the narration. The isnad must comprise upright and sincere individuals whose integrity is unquestionable.