Many Sufi practitioners are organized into a very diverse range of brotherhoods and sisterhoods. Although many orders ("tariqas") can be classified as Shi'a or Sunni or even both, there are a few that are clearly neither Shiah nor Sunni and so constitute a separate sphere of Islamic faith.
Sufis believe that their teachings are the essence of every religion, and indeed of the evolution of humanity as a whole. The central concept in Sufism is "love". Dervishes -- the name given to initiates of sufi orders -- believe that love is a projection of the essence of God to the universe. They believe that God desires to recognize beauty, and as if one looks at a mirror to see oneself, God "looks" at itself within the dynamics of nature. Since they believe that everything is a reflection of God, the school of Sufism practices to see the beauty inside the apparently ugly, and to open arms to what they believe as even the most evil one. This religious tolerance is expressed in Sufism via these lines which are often attributed to the famous Sufi philosopher and poet Mevlana Rumi (but which were penned before his time, according to some scholars): "Come, come, whoever you are. Worshiper, Wanderer, Lover of Leaving; ours is not a caravan of despair. Though you have broken your vows a thousand times...Come, come again, Come." (In many Unitarian Universalist youth groups this poem is sung with minor alterations)
Sufis teach in personal groups, believing that the intervention of the master is necessary for the growth of the pupil. They make extensive use of parables and metaphors, in such a way that the meaning is only reachable through a process of seeking for the utmost truth and knowledge of oneself.
Although philosophies vary between different Sufi sects, Sufism as a whole is primarily concerned with direct personal experience, and as such is often compared to Zen Buddhism and Gnosticism. The following metaphor, credited to an unknown Sufi scholar, helps describe this line of thought. "There are three ways of knowing a thing. Take for instance a flame. One can be told of the flame, one can see the flame with his own eyes, and finally one can reach out and be burned by it. In this way, we Sufis seek to be burned by God."
A large part of Muslim literature comes from the Sufis, who created great books of poetry (which include for example the Rubaiyat of Omar Khayyam, the Conference of the Birds and the Masnavi), all of which contain the profound, and hardly graspable, teachings of the Sufis.
Offshoots of Sufism in Africa include, for example, the Muslim brotherhoods of Senegal. The Sidis of Gujarat migrated from East Africa to India in the twelfth century.