A caliph is a religious and civil leader in a Muslim country. If you become a diplomat in the Middle East, you might have many discussions with caliphs.
Caliph comes from the Arabic word khalafa, meaning "successor" or "next in line." It was taken as a title by Abu-bekr, the first Islamic leader after the death of Mohammed, the prophet who founded the religion of Islam. All great Islamic leaders take the title caliph. Because caliph is an Anglicized version of an Arabic word, from a different alphabet, there are many spelling variations including calif, kalif, kaliph, khalif, and khalifah.