Sufism (Sufism) may be best described as a mystical practice that emphasizes certain unique rituals for guiding spiritual seekers into a direct encounter with God.

Sufism is a difficult term to actually define because its meaning is supposed to have derived from various words, with differing connotations:

Bishr ibn al–Harith has said that, “the sufi is he whose heart is sincere towards God.” Thus, one of the words from which Sufism is supposed to have derived is safa meaning pure — this due to the purity of the sufis’ heart.

Others have derived sufi from the word saff; this refers to the sufis’ “first rank” before God. Sufis believe that they are in a prominent position in relation to God. The term suffab — meaning, “People of the Bench” — and the word suf which refers to the Sufis habit of wearing wool are two more popular supposed derivations of the word sufi.

Sufism – What do Sufis believe about God?

When attempting to decide whether or not God is still in the act of creating, some Sufis are at odds; some say yes, he continues to create since Creator, Maker, and Former (one who formed) are his eternal attributes. Others say he did not become creator, maker, and former by performing these tasks; otherwise he would have been eternally deficient, only becoming complete through the act of creation.

God can do with his servants whatever he wills, because it is to the servant’s advantage.

One of the important rituals in Sufism is the zikr. During a zikr, one remembers God through meditation, chant, and movement — certain attributes of God are repeated until the seekers become “saturated” with God. This ritual supposedly, shatters and transforms them. As they spin and whirl around for hours, they reach a state of ecstasy and purity where the heart is only conscious of God. The seeker surrenders his or herself to total abandonment — a total emptying of self.

Reference: http://www.allaboutreligion.org/sufism.htm