There are many things in Islam which are not in the Qu'ran, but have been added later.
Such as the Hadith which is used in part to interpret the meaning of the Qur'an. The two main branches of Islam, Shi'at ul Ali (Shi'a) and the Sunni, have different hadith in which they consult. I'm not as well versed in Sunni Islam, but I believe the method they use to interpret the Qur'an is called Asbab al nazul, which identifies the reason each verse was given so as to put it in context for future understanding.
For instance, the idea of suicide bombs are nowhere in Islam, but it has been interpreted over the years that to die thus makes one a martyr, which is a key theme of the Qu'ran.
Martyrdom is honored in many of the sects of Islam, esp in Shi'a Islam (the state religion of Iran for example). And although the way to martyrdom is drastically different in Orthodoxy, it is highly honored with us as well. The wahhabist interpretation of Sunni Islam is fairly new, having it's origins in the 19th cent by Muhammad al Wahhab in what is now, I understand, in Sa'udi Arabia.
Other sects such as the Druze, Alawi, Sufi, Isma'ili, and Twelvers, as well as Islam as it's understood in Central Asia and the Caucus is even more unique and generally
devoid of such radical ideology.
Going back to the early years of Islam, when Muhammad was alive, it's been noted by various Orthodox saints as a Christian sect. Of coarse, what we see today on the evening news is something radically different.