Usury ( /ˈjuːʒəri/) is the practice of charging excessive, unreasonably high, and often illegal interest rates on loans.

Originally, when the charging of interest was still banned by Christian churches, usury simply meant the charging of interest at any rate (as well as charging a fee for the use of money, such as at a bureau de change). In countries where the charging of interest became acceptable, the term came to be used for interest above the rate allowed by law. The term is largely derived from Christian religious principles; Riba is the corresponding Arabic term and ribbit is the Hebrew word.

The pivotal change in the English-speaking world seems to have come with the permission to charge interest on lent money: particularly the 1545 act "An Act Against Usurie" (37 H.viii 9) of King Henry VIII of England (see book references).

Banking during Roman times was different from modern banking. During the Principate, most banking activities were conducted by private individuals, not by such large banking firms as exist today; almost all moneylenders in the Empire were private individuals because anybody that had any additional capital and wished to lend it out could easily do so.

Adam Smith (baptised 16 June 1723 – 17 July 1790 [OS: 5 June 1723 – 17 July 1790]) was a Scottish social philosopher and a pioneer of political economy. One of the key figures of the Scottish Enlightenment, Smith is the author of The Principles Which Lead and Direct Philosophical Enquiries, Illustrated by the History of Astronomy, prior to 1758, The Theory of Moral Sentiments, 1759, and An Inquiry into the Nature and Causes of the Wealth of Nations, 1776. The latter, usually abbreviated as The Wealth of Nations, is considered his magnum opus and the first modern work of economics. It earned him an enormous reputation and would become one of the most influential works ever published. Smith is widely cited as the father of modern economics and capitalism and is still among the most influential thinkers in the field of economics today. In 2009, Smith was named among the 'Greatest Scots' of all time, in a vote run by Scottish television channel STV.

Smith studied social philosophy at the University of Glasgow and at Balliol College in the University of Oxford, where he was one of the first students to benefit from scholarships set up by his fellow Glaswegian John Snell. After graduating, he delivered a successful series of public lectures at Edinburgh, leading him to collaborate with David Hume during the Scottish Enlightenment. Smith obtained a professorship at Glasgow teaching moral philosophy, and during this time he wrote and published The Theory of Moral Sentiments. In his later life, he took a tutoring position that allowed him to travel throughout Europe, where he met other intellectual leaders of his day. Smith then returned home and spent the next ten years writing The Wealth of Nations, publishing it in 1776. He died in 1790 at the age of 67.

Hamza Yusuf Hanson is an American Islamic scholar, and (with Zaid Shakir and Hatem Bazian) is co-founder of Zaytuna College in Berkeley, California, United States. He is a convert to Islam, and is one of the signatories of A Common Word Between Us and You, an open letter by Islamic scholars to Christian leaders, calling for peace and understanding. He has described the 9/11 attacks as "an act of 'mass murder, pure and simple'". Condemning the attacks, he has also stated "Islam was hijacked ... on that plane as an innocent victim".The Guardian newspaper in the United Kingdom reported that he "is arguably the west's most influential Islamic scholar" and added that "many Muslims find his views hard to stomach."

Hamza Yusuf was born to two academics in Washington State and raised in Northern California. In 1977, he became Muslim and subsequently traveled to the Muslim world and studied for ten years in the United Arab Emirates, Saudi Arabia, as well as North and West Africa. Hamza Yusuf spent four years studying in the United Arab Emirates and elsewhere in the Middle East. Later he traveled to West Africa and studied in Mauritania, Medina, Algeria, and Morocco under such scholars as Murabit al Haaj; Baya bin Salik, head of the Islamic court in Al-'Ain, United Arab Emirates; Muhammad Shaybani, Mufti of Abu Dhabi; Hamad al-Wali; and Muhammad al-Fatrati of Al Azhar University in Cairo, Egypt.^{[citation needed]} After more than a decade abroad, he returned to the United States and earned degrees in nursing from Imperial Valley College and religious studies at San José State University.^{[citation needed]}