OK, I gave it a shot. Just briefly, and a very broad short over view not intended to be guide, just a short version of some of the things I have learned about Islam.

Islam is a fractious religion similar to Christianity in that regard. It splintered early after Mohammads death in the 6th? Century with followers following different Imans. Some of these fractions became and are still violent. Islam spread with the sword particularly in the early days but often was benevolent to those conquered. Though often a special tax was levied on the non believers.
The religion at some point adopted certain Arabic traditions such as the head dress for woman.
Islam in its zenith had a tradition of study inspired by the words of Mohamand, in later years these same words would be used to change worldly studies to study of the Koran. (Quran) With some students reaching a high level of respect by being able to recite the entire book.
In recent history many Muslims have tried to no avail to revert this particular tradition, most notably, that past President of Indonesia. A hundred or so years ago there was a serious effort to reform, it failed.
There is no distinction in most Islamic countries between their religion and government.
Sharia law practice by Muslims comes from books that were early interpretations of the Koran. Sharia in its absolute form is barbaric. (The recent efforts to stone a woman to death in Tehran)
Naturally due to Islam’s expansion there was and is much friction between Islam and Christianity. With early Caliphates making deep in roads into Europe (Constantinople, Spain, etc…) this brought on the Crusades and much animus still exists by both sides as a consequence.