The landed gentry (also known as the squirearchy or simply gentry) is a largely historical British and Irish social class of landowners who could live entirely from rental income, or at least owned a country estate. The British element of the wider European class of gentry, while part of Britain's nobility and usually armigers, the gentry ranked below the British peerage in social status. Nevertheless, their economic base in land was often similar, and some of the landed gentry were wealthier than some peers. Many gentry were close relatives of peers, and it was not uncommon for gentry to marry into peerage. With or without noble title, owning rural land estates often brought with it the legal rights of the feudal lordship of the manor, and the less formal name or title of squire, in Scotland laird.

Generally lands passed by primogeniture, while the inheritances of daughters and younger sons were in cash or stocks, and relatively small. Typically the gentry farmed some of their land through employed managers, but leased most of it to tenant farmers. They also exploited timber and minerals (such as coal), and owned mills and other sources of income. Many heads of families also had careers in politics or the military, and the younger sons of the gentry provided a high proportion of the clergy, military officers, and lawyers. Successful burghers often used their accumulated wealth to buy country estates, with the aim of establishing themselves as landed gentry.

The decline of the gentry largely began with the great depression of British agriculture in the late 19th century; however, there are still many hereditary gentry in the UK. The book series Burke's Landed Gentry records the names of members of this class. The designation landed gentry originally referred exclusively to members of the upper class who were both landlords and commoners (in the British sense)—that is, they did not hold peerages. But by the late 19th century, the term was also applied to peers, such as the Duke of Westminster, who lived on landed estates.

The term gentry derives from gentrice, a word indicating high birth, high status, or gentleness. The term gradually came to be used for the lower ranks of the aristocracy, which along with the peerage had previously been considered part of the nobility. In the 16th and 17th centuries, writers referred to the peerage as the nobilitas major (Latin for "greater nobility") and the gentry as the nobilitas minor (Latin for "minor nobility"). Eventually, the terms nobility and gentry came to refer to completely separate classes.

The gentry were aristocratic landowners who were not peers. According to historian G. E. Mingay, the gentry were landowners whose wealth "made possible a certain kind of education, a standard of comfort, and a degree of leisure and a common interest in ways of spending it". Leisure distinguished gentry from businessmen who gained their wealth through work. The gentry did not enterprise or marketeer but were known most for working in management of estates; their income came largely from rents paid by tenant farmers living these estates. By the 17th century, the gentry was divided into four ranks:

In a historiographical survey, Peter Coss describes a number of approaches to deciding who was gentry. One is to view the gentry as those recognised legally as possessing gentility. However, Coss finds this method unsatisfactory because it "seems certain that gentility was widely felt and articulated within society long before legislation was in place to tell us so". Other historians define gentry by land ownership and income level, but there is still the problem of whether this should include professionals and town dwellers. Rosemary Horrox argues that an urban gentry existed in the 15th century. For some historians of early modern England, the gentry included families with coats of arms, but Coss notes that not all gentry were armigerous. Coss proposes that the gentry had three main characteristics: (1) landownership, (2) a nobility or gentility (shared with the peerage) that distinguished them from the rest of the population, and (3) a territorial-based collective identity and power over the larger population.

From the late 16th-century, the gentry emerged as the class most closely involved in politics, the military and law profession. It provided the bulk of Members of Parliament, with many gentry families maintaining political control in a certain locality over several generations (see List of political families in the United Kingdom). Owning land was a prerequisite for suffrage (the civil right to vote) in county constituencies until the Reform Act 1832; until then, Parliament was largely in the hands of the landowning class.^{[citation needed]}

The gentry ranked above the agricultural sector's middle class: the larger tenant farmers, who rented land from the landowners, and yeoman farmers, who were defined as "a person qualified by possessing free land of forty shillings annual [feudal] value, and who can serve on juries and vote for a Knight of the Shire. He is sometimes described as a small landowner, a farmer of the middle classes." Anthony Richard Wagner, Richmond Herald wrote that "a Yeoman would not normally have less than 100 acres" (40 hectares) and in social status is one step down from the gentry, but above, say, a husbandman. So while yeoman farmers owned enough land to support a comfortable lifestyle, they nevertheless farmed it themselves and were excluded from the "landed gentry" because they worked for a living, and were thus "in trade" as it was termed. Apart from a few "honourable" professions connected with the governing elite (the clergy of the established church, the officer corps of the British Armed Forces, the diplomatic and civil services, the bar or the judiciary), such occupation was considered demeaning by the upper classes, particularly by the 19th century, when the earlier mercantile endeavours of younger sons were increasingly discontinued. Younger sons, who could not expect to inherit the family estate, were instead urged into professions of state service. It became a pattern in many families that while the eldest son would inherit the estate and enter politics, the second son would join the army, the third son go into law profession, and the fourth son join the church.