The name is derived from the number one hundred, and in some areas it may once have referred to a hundred men under arms.
In England a hundred was the division of a shire for administrative, military and judicial purposes under the common law. Originally, when introduced by the Saxons between 613 and 1017, a hundred had enough land to sustain approximately one hundred households headed by a hundred-man or hundred eolder. He was responsible for administration, justice, and supplying military troops, as well as leading its forces. The office was not hereditary, but by the 10th century the office was selected from among a few outstanding families. In England, specifically, it has been suggested that 'hundred' referred to the amount of land sufficient to sustain one hundred families, defined as the land covered by one hundred "hides".
Hundreds were further divided. Larger or more populous hundreds were split into divisions (or in Sussex, half hundreds). All hundreds were divided into tithings, which contained ten households. Below that, the basic unit of land was called the hide, which was enough land to support one family and varied in size from 60 to 120 old acres, or 15 to 30 modern acres (6 to 12 ha) depending on the quality and fertility of the land. Compare with township.
Above the hundred was the shire under the control of a shire-reeve (or sheriff). Hundred boundaries were independent of both parish and county boundaries, although often aligned, meaning that a hundred could be split between counties (usually only a fraction), or a parish could be split between hundreds.
The system of hundreds was not as stable as the system of counties being established at the time, and lists frequently differ on how many hundreds a county has. The Domesday Book contained a radically different set of hundreds than that which would later become established, in many parts of the country. The number of hundreds in each county varied wildly. Leicestershire had six (up from four at Domesday), whereas Devon, nearly three times larger, had thirty-two.
Over time, the principal functions of the hundred became the administration of law and the keeping of the peace. By the twelfth century the hundred court was held twelve times a year. This was later increased to being held fortnightly, although an ordinance of 1234 reduced the frequency to once every three weeks. In some hundreds, courts were held at a fixed place; while in others, courts moved with each sitting to a different location. The main duties of the hundred court were the maintenance of the frankpledge system. Where the hundred was under the jurisdiction of the crown, the chief magistrate was a sheriff. However, many hundreds were in private hands, with the lordship of the hundred being attached to the principal manor of the area and becoming hereditary. Where a hundred was under a lord, a steward was appointed in place of a sheriff.
The importance of the hundred courts declined from the seventeenth century, and most of the powers were extinguished with the establishment of county courts in 1867. The remaining duty of the inhabitants of a hundred to make good damages caused by riot was ended in 1886, when the cost was transferred to the county police rate. Although hundreds had no administrative or legal role after this date, they have never been formally abolished.
By the 19th century several different single-purpose subdivisions of counties, such as poor law unions, sanitary districts, and highway districts sprang up, filling the administrative role previously played by hundreds.
Several ancient hundred names give their name to modern local government districts.
The Chiltern Hundreds are notable as a legal fiction, owing to a quirk of British Parliamentary law. A Crown Steward was appointed to maintain law and order in the area, but the position's duties ceased to be required in the 16th century, and the holder ceased to gain any benefits during the 17th century. The position has since been used as a procedural device to allow resignation from the House of Commons.
A wapentake is a term derived from the Old Norse vápnatak, the rough equivalent of an Anglo-Saxon hundred. The word denotes an administrative meeting place, typically a crossroads or a ford in a river. The origin of the word is not known. Folk etymology has it that voting would be denoted or conducted by the show of weapons, an idea perhaps suggested by references in The Germania of Tacitus or current practice in the Swiss canton of Appenzell Innerrhoden. According to other authorities weapons were not flourished at a Norse þing and "weapon taking" or vopnatak was the end of an assembly, when one was allowed to take weapons up again, providing another possible origin of the wapentake.
The Danelaw counties of Yorkshire, Derbyshire, Leicestershire, Northamptonshire, Nottinghamshire, Rutland and Lincolnshire were divided into wapentakes, just as most of the remainder of England was divided into hundreds.
In Yorkshire, a Norse wapentake usually replaced several Anglo-Saxon hundreds. This process was complete by 1086 in the North and West Ridings, but continued in the East Riding until the mid 12th century.
In Wales the hundred replaced traditional units such as the cantref (or cantred) or commote. Irish counties were divided into baronies.
The term hundare (hundred) was used in Svealand (the core region of early Sweden) and present-day Finland. Eventually that division was superseded by introducing the härad or Herred, which was the name in the rest of Scandinavia. This word was either derived from Proto-Germanic *harja-raiðō (warband) or Proto-Norse *harja-raiða (war equipment, cf. Wapentake).. Similar to skipreide: A part of the coast were the inhabitants were responsible for equipping and manning a war ship.
It is not entirely clear when hundreds were organised in the western part of Finland. The name of the province of Satakunta, roughly meaning hundred, hints at influences from the times before the Northern Crusades, Christianization, and incorporation into Sweden.
Counties in Delaware, New Jersey and Pennsylvania were divided into hundreds in the seventeenth century, in imitation of the British system. They survive in Delaware (see List of Delaware Counties and Hundreds), and were used as tax reporting and voting districts until the 1960s, but now serve no administrative role, their only current official legal use being in real-estate title descriptions.
The hundred was also used as a division of the county in Maryland. Carroll County, Maryland, was composed in 1836 by taking the following hundreds from Baltimore County: North Hundred, Pipe Creek Hundred, Delaware Upper Hundred, Delaware Lower Hundred and from Frederick County: Pipe Creek Hundred, Westminster Hundred, Unity Hundred, Burnt House Hundred, Piney Creek Hundred, and Taneytown Hundred.