Dhikr means 'rememberance' and to go into dhikr is to repeat or to recite the Divine Names as well as formulas or whole sentences. In Arabic, the word for 'human being' is insan, which means literally 'the one who has forgotten'. The dhikr thus helps us to remember the Divine qualities, and in that sense its effect is similar to that of Hindu and Buddhist mantras.
During the dhikr, we turn to the Divine, stepping out of our indifference and diving into the Divine, time and time again, to move into our heart, as the Sufis say. In Sufism the heart is the mirror. The dhikr is used to polish the heart so that it may shine in all its splendour and reflect the Divine mystery.