There are two main sacred texts: the Quran (Koran) and the Hadith (Hadeeth). These books teach and show the Islamic beliefs, values, and practices. They are also very important historical documents which tell the story of the origins of the Islamic faith. The most important one is the Quran though, because it is said to be the word of God given to Muhammad. Below is a video showing a prayer during a common Islam practice: Ramadan.
Muhammad's popularity threatened the people in power in Mecca, and Muhammad took his followers on a journey from Mecca to Medina in 622. The more he taught and spoke to people, the more people converted. At this time, monotheism was popular but so was the act of worshipping gods and goddesses. Muhammad made more people switch to worshipping Allah since many people worshipped idols.
Islam spread into Africa, Europe, and Asia shortly after the Prophet Muhammad's death in 632. Muslim leaders conquered many lands and overcame many geological boundaries. They were very successful at conquering lands that were weak, such as the Byzantine Empire (at that time). Below is a map showing all the empires and areas where Islam spread.
Islam had created a lot of controversy when it was first brought to Mecca. It started the Holy Wars or Crusades in which the Christians attempted to take the Holy Land back from the Muslims (when Islam expanded into more nations). This means Islam had created one of the most violent times in history which caused many wars based off religion following these. Today, Islam is very popular, coming in second place after Christianity. But there are still conflicts that come about with it, as with other religions. People, particularly Americans, have the most issues with the Muslim people. They disagree on government issues, war, and the most common: terrorism. Somehow Christians and Muslims started out as being friendly (Muhammad's era) then soon after Muhammad's death the differences pushed the two groups apart and put them against each other. Now the battle still continues on who is right and who is wrong.
Painting of the Prophet Muhammad (570-632)
Citations: bbc.co.uk (religion section), Patterns of Interaction Textbook, youtube.com (The Power of Prayer video), uwf.edu ,