The term tariqa refers to a Sufi order, led by a shaykh who is sometimes called a murshid, pir, or guide, but more often simply called a shaykh. The members of an order are called mureeds, or disciples, followers. Other terms for a Sufi are faqir, one who is poor or needy, generally meaning that one is in need of God.
Sufism is equally prevalent among Sunnis and Shi'is. Those sectarian denominations are not relevant to the category of Sufism, which adds a mystical dimension to either form of Islam. Obviously, not every Muslim is also a Sufi, but Sufism is not viewed by non-Sufi Muslims as another religion, but as another style of worship. Of course, such opinions vary from one place to another, in one country or another. In Pakistan and India, for example, general participation in Sufi festivals is extremely common, while in the United States, this is not usually the case. This is partly because the Sufi tradition in South Asia is deeply rooted in general cultural practices involving food, music, dancing, singing, and iconography, while in the United States, it is less rooted in local custom, and therefore less likely to appeal to a wide range of members and non-members.
Nearly every Sufi order takes its name from its original founder, and different tariqas could form offshoots once disciples attain the level of becoming teachers themselves. In some cases, a shaykh will name a successor, who will carry on the work and tradition of an order. In other cases, if no successor is named, disciples will elect a new leader. The mantle of leadership is not necessarily passed on to one's family members, though this often is what occurs.
Every Sufi order has and maintains a chain of tradition going back through the founder to his or her teachers and all the way back to Muhammad's teaching in the form of the hadith and as revealed in the Quran. This continuous chain is called a silsilah, and often comprises a simple list of names of the generations of teachers who have passed on methods and wisdom through the generations. For most Sufis who are Shi'i, the silsilah goes back Ali, the cousin and son-in-law of Muhammad. Sunni Sufis often link their silsilahs to Ali or to one or more of Muhammad's close Companions, such as Abu Bakr or Umar.
Each disciple is guided along the path of his or her spiritual development with specific instructions from theteacher. These instructions may consist of recitations that are to be read at specific times of day, and may comprise dozens or hundreds of repetitive supplications. All of these extra practices are in addition to the mandatory prayers incumbent on all Muslims, and they change and develop as the Sufi matures on his or her path.
Sufis are often cast as community changers in that their brand of Islamic worship seems conducive to more personalized and local expressions of religion. Thus, in South and Southeast Asia, Hindu music and practices fused with local Sufi practices in ways that distinguish that brand of Muslim life from other parts of the Islamic world. Sufi orders thus contributed to the spread of Islam in various regions, including Asia, sub-Saharan Africa, and North Africa. While some scholars overstate the role of Sufi missionaries in the conversion of South and Southeast Asia, it is true that Indonesia, the most populous Muslim country in the world, was affected by Muslim merchants and Sufis and never conquered by Muslim armies.