Sunni Islam is the largest branch of Islam; the second largest branch being Shia Islam. Sunni Muslims are referred to in Arabic as (أهل السنة والجماعة) “people of the tradition [of Muhammad] and the community”). In English, they are known as Sunnis or Sunnites.
Sunni Islam is referred to as the orthodox version of the religion. The word “Sunni” comes from the term Sunnah ( سنة), which refers to the sayings and actions of Muhammad that are recorded in hadiths (collections of narrations regarding Muhammad). Followers of Sunni Islam consider Sahih al-Bukhari and Sahih Muslim to be the authentic hadiths.
Source: Wikipedia
