Quran is an arabic word which means - one that is read. Quran refers to the last revelation of Almighty God or Allah. Quran was revealed to last Prophet of God -Prophet Muhammad (Peace be upon him). It was revealed in the duration of 23 years. Today it is in the form of book or CD. It contains 100% word of God. Quran has 114 chapters or 114 Surah. Each surah contains several sentences called Ayah. In total - Quran contains 6236 ayah. Quran is guidance for whole of humanity. It has been revealed for whole humanity till the end of this world.
Prophet Muhammad(peace be upon him) was born in mecca, Suadia Arab in 560 AD. At the age of 40 he was bestowed with Prophethood. Arch Angel gabriel brought the first revelation of God to Prophet Muhammad(peace be upon him). He also announced to Prophet Muhammad(peace be upon him) that Allah has chosen Prophet Muhammad(peace be upon him) as prophet. After this in a span of 23 years of time revelation of God would come to prophet Muhammad(peace be upon him) in several ways on different occassions. When revelation would come then Prophet Muhammad(peace be upon him) would recite it and his comapanions would memorize and write it. There were several companions of Prophet Muhammad who had memorized the Quran. Before death of Prophet Muhammad Quran was complete.Even today there are thousands of people around the globe who have memorized the whole Quran, giving no chance for any adulteration or changes.
There were several revelations of GOD
Almighty God is one. He is not 2 or 3 or 2.5! Almighty God is most powerful, most merciful. He is absolute and free from any weakness. Almighty God is The Creator. He created the whole universe, he is the master of all worlds, all creatures and all creations.
"Say! He is Allah one and only. He is absloute and eternal. He does not beget anyone, nor is he begotten. There is nothing like him"-Quran Surah Ikhlas(112)-Ayah 1-4
"Allah. There is no god but He,-the Living, the Self-subsisting, Eternal. No slumber can seize Him nor sleep. His are all things in the heavens and on earth. " Quran, Surah Baqrah(2)-Ayah 255
Almighty God created the first person on earth - Prophet Adam (Peace be upon him). After that generations after generations followed on the earth.For the guidance of mankind, almighty God has sent several revelations or words of God to earth.
"...and to every people(there is) a guide" Quran,Surah Rad 13:Ayah 7
These revelations were revealed to chosen people of God called messengers or Prophets.
There have been thousands of messengers of God on earth. Prophet Adam, Prophet Noah, prophet Moses, prophet Jesus, prophet Muhammad - (peace be upon them all) - they all were messenegers of God. They were given revelation from God for the guidance of mankind.
We may not know today name of all thousands of messengers. Similalry we may not know name of all revelations revealed by God. Holy Vedas are considered to be the earliest revelations of God.Similarly torah,zabur and injeel were revelations of God which were revealed to Prophet Moses, Prophet David and Prophet Jesus-(Peace be upon them all)-respectively. Today in its changed form - torah,zabur and injeel are called Holy Bible. No wonder word Injeel(Revelation that was given to Prohet Jesus(peace be upon him)) is mentioned 12 times in Quran. Similarly word Taurat(Revelation given to prophet Moses(peace be upon him)) is mentioned 18 times in Quran. Quran time and again confirms that they were revelations from the God.
"It is He(The GOD) Who has sent down the Book (the Qur'an) to you (O Muhammad صلى الله عليه وسلم) with truth, confirming what came before it. And He sent down the Taurat (Torah) and the Injeel (Gospel)" Quran, Surah Al imran 3: Ayah 3
Quran is the last revelation of GOD
Then finally Quran was revealed to last messenger prophet Muhammad (Peace be upon him). All the revelations prior to Quran were meant for limited time and limited people. That is why today we dont have 100% pure Holy vedas or Holy bible. Due to being revealed in old age, when there was no preserving mechanism, these scriptures could not be preserved with their 100% purity. But Utmost care was taken in preserving Quran. As it was revealed only 1400 years back and it was memorized by several people there was no chance of adulteration of Quran. Morever Allah himself promises to preserve Quran.
"We have, without doubt, sent down the Message; and We will assuredly guard it (from corruption)." Quran, Surah Hijar(15) Ayah 9
What about people who lived before revelation of Quran?
All the revelations of God were 100% word of God and whoever believed and followed it were muslims. All the messengers were pious people,they submitted to God and they preached the religion of God or islam. Quran prohibits us to make any distinction among prophets.
"Say, "We believe in Allah and that which has been sent down to us and that which has been sent down to Ibrahim (Abraham), Isma'il (Ishmael), Ishaq (Isaac), Ya'qub (Jacob), and to Al-Asbat [the offspring of the twelve sons of Ya'qub (Jacob)], and that which has been given to Musa (Moses) and 'Îsa (Jesus), and that which has been given to the Prophets from their Lord. We make no distinction between any of them, and to Him we have submitted (in Islam)."
( سورة البقرة , Al-Baqara, Chapter #2, Verse #136)
"The Messenger believes in what has been sent down to him from his Lord, and (so do) the believers. Each one believes in Allah, His Angels, His Books, and His Messengers. (They say), "We make no distinction between one another of His Messengers" - and they say, "We hear, and we obey. (We seek) Your Forgiveness, our Lord, and to You is the return (of all)."
( سورة البقرة , Al-Baqara, Chapter #2, Verse #285)
"Say: "We believe in Allah and in what has been sent down to us, and what was sent down to Ibrahim (Abraham), Isma'il (Ishmael), Ishaq (Isaac), Ya'qub (Jacob) and Al-Asbat [the offspring of the twelve sons of Ya'qub (Jacob)] and what was given to Musa (Moses), 'Îsa (Jesus) and the Prophets from their Lord. We make no distinction between one another among them and to Him (Allah) we have submitted (in Islam)."
( سورة آل عمران , Aal-e-Imran, Chapter #3, Verse #84)
"And those who believe in Allah and His Messengers and make no distinction between any of them (Messengers), We shall give them their rewards; and Allah is Ever Oft-Forgiving, Most Merciful"
( سورة النساء , An-Nisa, Chapter #4, Verse #152)
Hence,those people who came before advent of Prophet Muhammad(peace be upon him) and followed teachings of their prophet or whatever was revelaed from God - were muslims or Submitters to God.
What Quran contains?
Quran is book of guidance for humanity. It covers various aspects of human life, viz: Spiritual, social, family,economic,poitical. Quran guides us how to lead our life so that we attain real salvation. Quran commands mankind to worship only One Almighty God. Quran exhorts its reader to ponder over the meaning of Quran, use intellect, understand the Quran, implement in life, look at various signs of Allah,follow what has been revealed from God. Quran speaks about several scientifc facts that were unknows to people 1400 years back. Quran is miracle of all miracles. Previous prophets were given some or the other miraclous power. The miracle given to Prophet Muhammad(Peace be upon him) is Quran. Quran challenges its opponents to prove it wrong. Quran is mercy for those who humble themself to their lord.
Quran is word of God. It was not sent for a particular tribe/group/nation/race; rather it was sent for whole mankind.
"Ramadhan is the (month) in which was sent down the Qur'an, as a guide to mankind, also clear (Signs) for guidance and judgment..." Quran,Surah Baqrah 2:185
It was the month of ramdhan when first revelation of Quran came. It has been revealed for whole humanity. Whosoever follows it will follow for his/her own guidance. Quran is the criteria to judge right from wrong. Let us submit to our creator-Allah and follow his commandments.
Note: Everything written is my level best unbiased understanding. Kindly mail me for criticism/suggestion/feedback firstname.lastname@example.org.