The followers of Islam are called Muslims. We should not confuse Muslims with Arabs. Muslims may be Arabs, or they may be Turks, Persians, Indians, Pakistanis, Indonesians, Europeans, Africans, Americans, Chinese, or any other nationality. Islam is not limited to any nationality or race.
Arabs, also, are not limited to only one religion. An Arab may be a Muslim, a Jew, a Christian, an atheist, or part of any other belief system. Any person who adopts the Arab language as his or her mother tongue is called an Arab.
While there are over one billion Muslims in the world, there are about 200 million Arabs, among whom about ten percent are not Muslim. Thus, Arab Muslims constitute only about twenty percent of the Muslim population of the world.
The language of the Quran, the Holy Book of Islam, is Arabic. Muslims all over the world try to learn Arabic so that they may be able to read the Quran and understand its meaning. They pray in the language of the Quran, but supplications to God may be in any language.