A mystic tradition of Islam, which is based on the pursuit of spiritual truth as a definite goal to attain. In modern language it might also be referred to as Islamic spirituality or Islamic mysticism. Sufism focuses on the internal aspects of Islam, such as perfecting the aspect of sincerity of faith and fighting one's ego. Sufi practitioners are organised into a diverse range of brotherhoods and sisterhoods, with a wide diversity of thought. Sufi orders ("tariqas") can be Shi'a, Sunni, both or neither.