The religious practices of Muslims are enumerated in the Five Pillars of Islam: the declaration of faith, daily prayers, fasting during the month of Ramadan, almsgiving, and the pilgrimage to Mecca at least once in a lifetime. To become a Muslim and to convert to Islam, it is essential to utter the Shahada, one of the Five Pillars of Islam, a declaration of faith and trust that professes that there is only one God and that Muhammad is God's messenger. It is a set statement normally recited in Arabic: lā ʾilāha ʾillā-llāhu muḥammadun rasūlu-llāh "There is no god but Allah, Muhammad is the messenger of God." In Sunni Islam, the shahada has two parts: la ilaha illa'llah, and Muhammadun rasul Allah, which are sometimes referred to as the first shahada and the second shahada. The first statement of the shahada is also known as the tahlīl. In Shia Islam, the shahada also has a third part, a phrase concerning Ali, the first Shia Imam and the fourth Rashid caliph of Sunni Islam: وعليٌ وليُّ الله, which translates to "Ali is the wali of God".
The word muslim is the active participle of the same verb of which islām is a verbal noun, based on the triliteralS-L-M "to be whole, intact". A female adherent is a muslima . The plural form in Arabic is muslimūn or muslimīn, and its feminine equivalent is muslimāt. The ordinary word in English is "Muslim". The word Mosalman is a common equivalent for Muslim used in Central and South Asia. In English it was sometimes spelled Mussulman and has become archaic in usage. Until at least the mid-1960s, many English-language writers used the term Mohammedans or Mahometans. Although such terms were not necessarily intended to be pejorative, Muslims argue that the terms are offensive because they allegedly imply that Muslims worship Muhammad rather than God. Other obsolete terms include Muslimite and Muslimist.
The Qur'an describes many prophets and messengers within Judaism and Christianity, and their respective followers, as Muslim: Adam, Noah, Abraham, Ishmael, Jacob, Moses, and Jesus and his apostles are all considered to be Muslims in the Qur'an. The Qur'an states that these men were Muslims because they submitted to God, preached His message and upheld His values, which included praying, charity, fasting and pilgrimage. Thus, in Surah 3:52 of the Qur'an, Jesus' disciples tell him, "We believe in God; and you be our witness that we are Muslims." In Muslim belief, before the Qur'an, God had given the Tawrat to Moses, the Zabur to David and the Injil to Jesus, who are all considered important Muslim prophets.
The most populous Muslim-majority country is Indonesia, home to 12.7% of the world's Muslims, followed by Pakistan, Bangladesh, and Egypt. About 20% of the world's Muslims live in the Middle East and North Africa. Sizable minorities are also found in India, China, Ethiopia, the Americas, Australia and parts of Europe. The country with the highest proportion of self-described Muslims as a proportion of its total population is Morocco. Converts and immigrant communities are found in almost every part of the world. Over 75–90% of Muslims are Sunni. The second and third largest sects, Shia and Ahmadiyya, make up 10–20%, and 1% respectively. With about 1.9 billion followers, almost a quarter of earth's population, Islam is the second-largest and the fastest-growing religion in the world. due primarily to the young age and high fertility rate of Muslims, with Muslim having a rate of compared to the world average of. According to the same study, religious switching has no impact on Muslim population, since the number of people who embrace Islam and those who leave Islam are roughly equal. A Pew Center study in 2016 found that Muslims have the highest number of adherents under the age of 15 of any major religion, while only 7% are aged 60+. According to the same study, Muslims have the highest fertility rates of any major religious group. The study also found that Muslims have the lowest average levels of education with an average of 5.6 years of schooling, though both groups have made the largest gains in educational attainment in recent decades among major religions. About 36% of all Muslims have no formal schooling, and Muslims have the lowest average levels of higher education of any major religious group, with only 8% having graduate and post-graduate degrees.