A Muslim is someone who follows or practices Islam, a monotheistic Abrahamic religion. Muslims consider the Quran (Koran), their holy book, to be the verbatim word of God as revealed to the Islamic prophet and messenger Muhammad. The majority of Muslims also follow the teachings and practices of Muhammad ( sunnah ) as recorded in traditional accounts ( hadith ).  "Muslim" is an Arabic word meaning "one who submits (to God)". 
The beliefs of Muslims include: that God ( Arabic: الله Allāh ) is eternal, transcendent and absolutely one ( tawhid or monotheism); that God is incomparable, self-sustaining and neither begets nor was begotten; that Islam is the complete and universal version of a primordial faith that has been revealed before through many prophets including Abraham, Moses, Ishmael and Jesus ;  that these previous messages and revelations have been partially changed or corrupted over time ( tahrif ) and that the Qur'an is the final unaltered revelation from God (The Final Testament). 
Who counts as a Muslim
The religious practices of Muslims are enumerated in the Five Pillars of Islam: the declaration of faith ( shahadah ), daily prayers ( salat ), fasting during the month of Ramadan ( sawm ), almsgiving ( zakat ), and the pilgrimage to Mecca ( hajj ) at least once in a lifetime.  
To become a Muslim and to convert to Islam 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 ( Allah) and that Muhammad is God's messenger.  It is a set statement normally recited in Arabic: lā ʾilāha ʾillā-llāhu muḥammadun rasūlu-llāh ( لَا إِلٰهَ إِلَّا الله مُحَمَّدٌ رَسُولُ الله ) "There is no god but Allah, (and) Muhammad is the messenger of God." 
In Sunni Islam, the shahada has two parts: la ilaha illa'llah (there is no god but God), and Muhammadun rasul Allah ( Muhammad is the messenger of God), 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 ( wa ʿalīyyun walīyyu-llāh ), which translates to "Ali is the wali of God.
The word muslim ( Arabic: مسلم , IPA: [ˈmʊslɪm] ; English: /ˈmʌzlɪm/ , /ˈmʊzlɪm/ , /ˈmʊslɪm/ or moslem /ˈmɒzləm/ , /ˈmɒsləm/  ) is the active participle of the same verb of which islām is a verbal noun, based on the triliteral S-L-M "to be whole, intact". A female adherent is a muslima ( Arabic: مسلمة ) (also transliterated as "Muslimah"  ). The plural form in Arabic is muslimūn ( مسلمون ) or muslimīn ( مسلمين ), and its feminine equivalent is muslimāt ( مسلمات ). The Arabic form muslimun is the stem IV participle of the triliteral S-L-M .
The ordinary word in English is "Muslim". It is sometimes transliterated as "Moslem", which is an older spelling. The word Mosalman ( Persian: مسلمان , alternatively Mussalman ) is a common equivalent for Muslim used in Central Asia. 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 .
Musulmán / Mosalmán ( Persian: مسلمان ) is a synonym for Muslim and is modified from Arabic. It is the origin of the Spanish word musulmán , the (dated) German Muselmann , the French word musulman , the Polish words muzułmanin and muzułmański , the Portuguese word muçulmano , the Italian word mussulmano or musulmano , the Romanian word musulman and the Greek word μουσουλμάνος (all used for a Muslim).  In English it was sometimes spelled Mussulman and has become archaic in usage.
Apart from Persian, Spanish, Polish, Portuguese, Italian, and Greek, the term could be found, with obvious local differences, in Armenian, Dari, Pashto, Urdu, Hindi, Bengali, Marathi, Panjabi, Turkish, Kazakh, Uzbek, Kyrgyz, Azeri, Maltese, Hungarian, Czech, Bosnian, Bulgarian, Russian, Serbian, Ukrainian, Romanian, Dutch, and Sanskrit.
The Muslim philosopher Ibn Arabi said:
A Muslim is a person who has dedicated his worship exclusively to God... Islam means making one's religion and faith God's alone.
Used to describe earlier prophets in the Qur'an
The Qur'an describes many prophets and messengers within Judaism and Christianity, and their respective followers, as Muslim: Adam, Noah, Abraham, Jacob, Moses, Ishmael, 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 ( wa-shahad be anna muslimūn )." In Muslim belief, before the Qur'an, God had given the Tawrat ( Torah, Old Testament) to Moses, the Zabur ( Psalms) to David and the Injil ( Gospel, New Testament) 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 (11.0%), Bangladesh (9.2%), and Egypt (4.9%).  About 20% of the world's Muslims lives in the Middle East and North Africa. 
Sizable minorities are also found in India, China, Russia, 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.
With about 1.6 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 (3.1) compared to the world average of (2.5). 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 2011 found that Muslims have the highest number of adherents under the age of 15 (or- 34% of the total Muslim population) of any major religion, while only 7% are aged 60+ (the smallest percentage of any major religion). According to the same study, Muslims have also the highest fertility rates (3.1) than any other major religious group. 
- Non-denominational Muslim
- Islamic schools and branches
- Lists of Muslims
- Muslim holidays
- Muslim world
- Original source estimated 87–90% of Muslims to adhere to Sunni Islam but counted almost all non-denominational Muslims as Sunni. To get a more accurate estimation, percentage of Non-denominational Muslims (15–20%) was subtracted from the original estimation
- also known as "infinitive"