A unitary authority is a type of local authority that is responsible for all local government functions within its area. This is different from a system where local government functions are divided between different authorities.

Typically unitary authorities cover large towns or cities, which are large enough to be independent of county or regional administration. Sometimes they consist of counties which have no lower level of administration.

United Kingdom
In the United Kingdom, "Unitary Authorities" are English councils which are responsible for almost all local government functions within their areas.

This is opposed to the system of local government which still exists in most of England, where local government functions are divided between county councils and district councils.

Until 1996 a similar system existed in Scotland and Wales but this has now been replaced by a fully unitary system. The unitary system has existed in Northern Ireland since 1973. when the administrative responsibilities of the Counties of Northern Ireland were replaced by a system of 26 unitary authorities.

England
Some cities, large towns and groups of neighbouring towns are unitary authorities and independent from county councils and some English counties, such as Rutland, Herefordshire and the Isle of Wight, have so small populations that the entire county is a unitary authority.

In practice most unitary authorities in the UK are not entirely unitary, as they often run some services on a joint basis with other authorities, these typically include policing, fire services, and sometimes waste disposal and public transport. In addition some unitary authorities contain civil parishes, which effectively form another limited  of local government

When the metropolitan councils were abolished in 1986 their functions were given to the boroughs. These became unitary authorities in all but name.

Other countries
Similar institituions exist in other countries, which although not called unitary authorities, are similar in concept.

United States
In the United States an Independent city or a consolidated city-county is roughly equivalent to a unitary authority. The city might be separate from any county government, as in Virginia, or merged with a county government, as in San Francisco, California, or as is common in Florida. Another type of local government that is roughly equivalent to a unitary authority is a county when there are no municipal or township governments in the county. That is the case in Arlington County, Virginia, and Baltimore County, Maryland.

Canada
Unitary authorities or single-tier municipalities exist as a single level of government in a province that otherwise has two levels of local government. One should not confuse municipalities in provinces with no upper-level of local government as single-tier municipalities, as these are the only level of local government in that province.

Germany
In Germany a kreisfreie Stadt is the equivalent term for a city which is responsible for the local and the Kreis (district) administrative level.

Political systems
Local government in England
Local government in the United States
Government of Canada
Government of New Zealand

ru:Унитарные единицы Англии