dhikr
Dhikr (also pronounced zikr) means remembrance or invocation of God (Al-Lah)'s name. There are 3 main kinds of dhikr and also 3 different ways of doing it. The three main kinds are:
1- dhikr of Divine Names
2-Darood Sharif (blessing sent to Prophet Muhammad s.a.w.)
3-kalima (La ilaha ill'lal-Lah Hu) (lit., there is no deity, except You my Al-Lah).
3-diffrent ways of doing dhikr:
1- with tongue (dhikrwith sound) (dhirk al-lisani)
2- by Heart (dhikr al-qalbi) (Quite dhikr)
3- by the spirit (dhikr ar-Ruhi)
The third one is of the highest degree and can be achieved only after years of practice. The dhikrzikr can be done individually or in a group. The Sufi is supposed to do dhikrwith every breath 24/7. Traditionally some Divine Names are given by Sufi-Master for healing or achieving or manifesting other objectives in life e.g., jobs etc.
According to Sufism, each Divine Name is a form of energy(potential and kinetic); with repeated invocation that energy gets stored in our heart and soul and turns from potential to kinetic energy bringing manifestations, healings, prayers(supplication) are answered faster, people overcome obstacles in life etc.
Group dhikr opens up the spiritual heart and like the old saying "positive begets positive and negative begets negative" the aftereffects of group dhikr can be felt long afterwards.
There are many verses in Qur'an suggestive of remembrance. Through dhikr a Sufi creates a "link" and a loving relationship with his/her Creator and Sustainer.
After all we tend to remember or reminiscent more about those whom we love.
See also
Third Kalima