Islamic religious leaders have traditionally been people who, as part of the clerisy, mosque, or government, performed a prominent role within their community or nation.
In the broader sense, it refers to those who have studied a broad range of essentially Islamic disciplines for several years, for example the hadith and the muhaddith.
They represent the Ijmah, or Islamic consensus of the Ummah on religious issues; this does not mean that there can be no disputes - far from it - but they should be aware of what counts as the main consensual opinion, of other dissenting views and their objections.
Caliph was first used, in the 7th century AD, for Abu Bakr, who was elected head of the Muslim community after the Prophet Muhammad's death.
It is considered by Muslims in some countries to indicate the highest authority in Sunni Islam for Islamic jurisprudence, The grand Imam holds a great influence on followers of the theological Ash'ari and Maturidi traditions worldwide, while the defenders of the Athari and Salafi ideologies find their leaders in the Arabian Peninsula.
The title of "Grand Mufti" (Arabic: مفتي عام) refers to the highest official of religious law in some Muslim countries.
In that case, the traditional Mufti may well be replaced by a university or madrasa professor who informally functions as adviser to the local Muslim community in religious matters such as inheritance, divorce, etc.
In early modern times it is mainly used for the headmaster of an Islamic Boarding School (in Indonesia known as pondok pesantren).
Due to animistic belief of ancient Javanese people, the title "Kyai" is also used to call almost all persons and things venerated.