Historically, a sheriff was a legal official with responsibility for a shire, the term being a contraction of
"shire reeve" (Old English Old English 
In British English, the political or legal office of a sheriff, term of office of a sheriff, or jurisdiction of a sheriff, is called a shrievalty in England and Wales, and a sheriffdom in Scotland.
In modern times, the specific combination of legal, political and ceremonial duties of a sheriff varies greatly from country to country.
- In England, Northern Ireland, or Wales, a sheriff (or high sheriff) is a ceremonial county or city official.
- In Scotland, sheriffs are judges.
- In the Republic of Ireland, in some counties and in the cities of Dublin and Cork, sheriffs are legal officials similar to bailiffs.
- In the United States, a sheriff is a sworn law enforcement officer, whose duties vary across states and counties. A sheriff is generally an elected county official, with duties that typically include policing unincorporated areas, maintaining county jails, providing security to courts in the county, and (in some states) serving warrants and court papers. In addition to these policing and correction services, a sheriff is often responsible for enforcing civil law within the jurisdiction.
- In Canada, sheriffs exist in most provinces. The provincial sheriff services generally manage and transport court prisoners, serve court orders, and in some provinces sheriffs provide security for the court system, protect public officials, support investigations by local police services and in Alberta, sheriffs carry out traffic enforcement.
- In Australia and South Africa sheriffs are legal officials similar to bailiffs. In these countries there is no link maintained between counties and sheriffs.
- In India, a sheriff is a largely ceremonial office in some major cities.