Detail of William and Mary from the ceiling of the Painted Hall
The phrase William and Mary usually refers to the coregency over the Kingdoms of England, Scotland and Ireland, of spouses (and first-cousins) King William III & II and Queen Mary II. Their joint reign began in February 1689 after they were offered the throne by the Convention Parliament irregularly summoned by William after his successful invasion of England in 1688, the so-called Glorious Revolution. They replaced James II & VII, Mary's father and William's uncle and father-in-law, who fled the country. Parliament offered William and Mary a co-regency, at the couple's behest. After Mary died in 1694, William ruled alone until his death in 1702. William and Mary were childless and were ultimately succeeded by Mary's younger sister, Anne.
To end the Glorious Revolution, William and Mary signed the English Bill of Rights of 1689. This action both signaled the end of several centuries of tension and conflict between the crown and parliament, and the end of the idea that England would be restored to Roman Catholicism, King William being a Protestant leader. The Bill of Rights also inspired the English colonists in the Thirteen Colonies to revolt against the rule of King James II and his proposed changes in colonial governance. These revolts occurred in the colonies of Massachusetts, New York, and Maryland.
Stamp duty was first introduced into England during this reign, by an act of 1694 titled "An act for granting to their Majesties several duties upon vellum, parchment and paper, for four years, towards carrying on the war against France".
Their names were lent to the second institution of higher learning in the United States, The College of William and Mary, which was founded in 1693 under a royal charter.