During the early Muslim conquests, the Muslim Arabs led by Khalid ibn al-Walid conquered the Sassanid Persian Empire and more than half of the Byzantine Roman Empire, establishing the Arab Empire across the Middle East, Central Asia, and North Africa, followed by further expansions across Pakistan, southern Italy and the Iberian Peninsula.

Rosanna Gorini writes:
"According to the majority of the historians al-Haytham was the pioneer of the modern scientific method. With his book he changed the meaning of the term optics and established experiments as the norm of proof in the field. His investigations are based not on abstract theories, but on experimental evidences and his experiments were systematic and repeatable."

Robert Briffault wrote in The Making of Humanity:
"The debt of our science to that of the Arabs does not consist in startling discoveries or revolutionary theories; science owes a great deal more to Arab culture, it owes its existence. The ancient world was, as we saw, pre- scientific. The astronomy and mathematics of the Greeks were a foreign importation never thoroughly acclimatized in Greek culture. The Greeks systematized, generalized and theorized, but the patient ways of investigation, the accumulation of positive knowledge, the minute methods of science, detailed and prolonged observation, experimental inquiry, were altogether alien to the Greek temperament. What we call science arose in Europe as a result of a new spirit of inquiry, of new methods of investigation, of the method of experiment, observation, measurement, of the development of mathematics in a form unknown to the Greeks. That spirit and those methods were introduced into the European world by the Arabs."

Science is the most momentous contribution of Arab civilization to the modern world, but its fruits were slow in ripening. Not until long after Moorish culture had sunk back into darkness did the giant to which it had given birth, rise in his might. It was not science only which brought Europe back to life. Other and manifold influences from the civilization of Islam communicated its first glow to European life."

George Sarton, the father of the history of science, wrote:
"The main, as well as the least obvious, achievement of the Middle Ages was the creation of the experimental spirit and this was primarily due to the Muslims down to the 12th century."

Oliver Joseph Lodge wrote in the Pioneers of Science:
"The only effective link between the old and the new science is afforded by the Arabs. The dark ages come as an utter gap in the scientific history of Europe, and for more than a thousand years there was not a scientific man of note except in Arabia."

Muhammad Iqbal, Allama wrote in "The Reconstruction of Religious Thought in Islam":
"Thus the experimental method, reason and observation introduced by the Arabs were responsible for the rapid advancement of science during the medieval times."

A number of important institutions previously unknown in the ancient world have their origins in the medieval Islamic world, with the most notable examples being: the public hospital (which replaced healing temples and sleep temples) and psychiatric hospital, the public library and lending library, the academic degree-granting university, the astronomical observatory as a research institute (as opposed to an observation post as was the case in ancient times) and the trust 

The first universities which issued diplomas were the Bimaristan medical university-hospitals of the medieval Islamic world, where medical diplomas were issued to students of Islamic medicine who were qualified to be practicing doctors of medicine from the 9th century. 

Sir John Bagot Glubb wrote:
"By Mamun's time medical schools were extremely active in Baghdad. The first free public hospital was opened in Baghdad during the Caliphate of Haroon-ar-Rashid. As the system developed, physicians and surgeons were appointed who gave lectures to medical students and issued diplomas to those who were considered qualified to practice. The first hospital in Egypt was opened in 872 AD and thereafter public hospitals sprang up all over the empire from Spain and the Maghrib to Persia."

The Guinness Book of World Records recognizes the University of Al Karaouine in Fez, Morocco as the oldest university in the world with its founding in 859. Al-Azhar University, founded in Cairo, Egypt in the 10th century, offered a variety of academic degrees, including postgraduate degrees, and is often considered the first full-fledged university.

A number of distinct features of the modern library were introduced in the Islamic world, where libraries not only served as a collection of manuscripts as was the case in ancient libraries, but also as a public library and lending library, a centre for the instruction and spread of sciences and ideas, a place for meetings and discussions, and sometimes as a lodging for scholars or boarding school for pupils. The concept of the library catalog was also introduced in medieval Islamic libraries, where books were organized into specific genres and categories.

Another common feature during the Islamic Golden Age was the large number of Muslim polymaths or "universal geniuses", scholars who contributed to many different fields of knowledge. Muslim polymaths were known as "Hakeems" and they had a wide breadth of knowledge in many different fields of religious and secular learning, comparable to the later "Renaissance Men", such as Leonardo da Vinci, of the European Renaissance period. Polymath scholars were so common during the Islamic Golden Age that it was rare to find a scholar who specialized in any single field at the time. Notable Muslim polymaths included al-Biruni, al-Jahiz, al-Kindi, Abu Bakr Muhammad al-Razi, Ibn Sina, al-Idrisi, Ibn Bajja, Omar Khayyam, Ibn Zuhr, Ibn Tufayl, Ibn Rushd, al-Suyuti Geber, al-Khwarizmi, the Banu Musa, Abbas Ibn Firnas, al-Farabi, al-Masudi, al-Muqaddasi, Alhacen, Omar Khayyám, al-Ghazali, al-Khazini, Avempace, al-Jazari, Ibn al-Nafis, Nasir al-Din al-Tusi, Ibn al-Shatir, Ibn Khaldun, and Taqi al-Din, among many others.