Arabic is the language of the Qur'an, the Muslim holy book, and is therefore understood on some level by all devout Muslims, regardless of where they live. Although Muslims are spread throughout the world, the majority are grouped in four key language areas. However, all Muslims understand simple phrases like "hello" and "goodbye" in Arabic, although some may have local alternatives.

Arabic

Although not all Muslims speak Arabic as a first language, and not everyone who speaks Arabic is a Muslim, Arabic is the "lingua franca" of Islam. According to the Hadith, or Islamic religious teaching, Allah told Adam to take his greeting from the Angels, and pass it on to his offspring. "Hello" in Arabic is therefore "As-Salaam-Alaikum," or "Peace be Upon You," to which the response is "Wa-Alaikum-Salaam," or "Unto You be Peace." This can be shortened to just "Salaam" among peers or close friends. "Goodbye" in Arabic is "ma'aasalaama." All of these terms are understood throughout the Muslim world. The Hadith also states that when followers of Muhammad met, they would shake hands, although if one had been on a journey, they would embrace. Embracing is also permitted during special occasions, such as Eid or other festivals. When meeting elders or seniors, it is said in the Hadith that a Muslim must stand and kiss the hand of the elder, who reciprocates with a kiss to the forehead. However, the Hadith also forbids touching between men and women, even as a greeting.

Farsi

Farsi is the proper name for the Persian language, and is spoken in Iran, Afghanistan and Tajikistan, as well as in other communities in the Islamic world. "Hello" in Farsi is "salām," and "goodbye" is "khodā hāfez." Although Farsi has a number of more complex phrases for both "hello" and "goodbye," these are the ones that Farsi speakers use most commonly, and they are understood throughout the Persian world. Although both are somewhat religious phrases -- "goodbye" means "God protect" -- they are used in non-religious contexts as well.

Turkish

Because of the historical Ottoman Empire, as well as geographical proximity, Turkish is regarded as an important language in the Islamic world. Although officially a secular state, the majority of Turks are Muslim, and the Turkish language has many similarities with Arabic. "Hello" in Turkish is "merhaba," and "Goodbye" is "Hoschakal" in a more formal setting, or "Gule Gule" between friends or close relatives. However, some Turks may use the Arabic phrases instead of their Turkish equivalents.

Indonesian

According to Michigan State University, Indonesia has the largest Muslim population in the world -- one out of eight Muslims in the world is Indonesian. However, the Indonesian language is not generally understood in the rest of the Islamic world. "Good day" in Indonesian is "selamat siang," while "good evening" is "selamat malam." "Goodbye" is "selamat jalan" if someone else is leaving and "selamat tinggal" if someone else is staying. Muslim Indonesians also often use Arabic greetings.