The office of sheriff owes its origins to the Anglo-Saxon system of local self government, where the "shire reeve" was the chief of a group of several hundred families. The whole realm was parted and divided into shires with the reeve of the shire being the chief officer to the King within that shire. The Sheriff assumed a particular role under Alfred the Great for the maintenance of law and order in each county.
Each of the towns divided into groups of ten families, called tithings. Each tithing elected a leader called a tithingman. The next level of government was a group of ten tithings (or 100 families), and this group elected its own chief. The Anglo-Saxon word for chief was gerefa, later shortened to reeve.
During the next two centuries, groups of hundreds banded together to form a new, higher unit of government called the shire. The shire was the forerunner of the modern county. Each shire had a chief (reeve) as well, and the more powerful official became known as a shire-reeve. The word shire-reeve became the modern English word sheriff — the chief of the county.
Where originally in Anglo-Saxon England the reeve was a senior official with local responsibilities under the king, after the Norman conquest, it was an office held by a man of lower rank appointed as manager of a manor and overseer of the peasants. In this later role, historian H. R. Loyn observes, "he is the earliest English specialist in estate management."
In some manors the reeve was appointed by the lord of the manor, but in others he was elected by the peasants, subject or not to a right of veto by the lord. It depended on the custom of the manor, but there was an increasing tendency for election to be favoured. No doubt an elected reeve was more willingly obeyed and sometimes the peasants generally would be made financially liable if an elected reeve defaulted.
He oversaw the work performed by peasants as an obligation to the lord of the manor on the estate. He was also responsible for many aspects of the finances of the manor such as the sale of produce, collection of monies and payment of accounts. He was usually himself a peasant and was subject to the steward, but the steward might not always be resident on the manor and would not usually concern himself with day to day working. The reeve was chosen once a year, generally at Michaelmas, but a good man who carried out his duties efficiently and was trusted by the lord and the peasants was likely to stay in office more or less permanently. By the 14th century the reeve was often a permanent officer of the manor.