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 Allah)". 

The beliefs of Muslims include: that God 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). 

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" () "There is no god but Allah , (and) Muhammad is the messenger of God."
Do they believe in other prophets?
many prophets including Abraham, Moses, Ishmael and Jesus; 