Sufi is called to an extreme true religious muslim person.
When he/she die then people make there buried place as shrine and start almost (not exactly) worshipping this place. Thy start asking their will from this dead person.
Such practice (which is against the core and basic principle of Islam) are called as sufism.
People (not all) from both Sunni and Shia do practice this sufism activity.
Sufism mainly grown in Turkey, Iran, Iran and Indian subcontinent and still it is practicising in these countries.
Arab world is almost isolated from this practice and they are true follower of Islam (upto some extent).
In India most of the sufism practicing muslims are illitrate and indulge in all type of criminal activity.
