A more thorough explanation:

A county is a large area of land that is governed by a local government within a state. It is considered a political subdivision and a quasi-corporation. Every county exists as a result of a sovereign act of legislation, either constitutional or statutory, separating it from the rest of the state as an integral part of its territory and establishing it as one of the primary divisions of the state for purposes of civil administration.

For example, Los Angeles County is a county in California that has its own government and is responsible for providing services to its residents, such as law enforcement, public health, and social services. Another example is Cook County in Illinois, which includes the city of Chicago and its suburbs.

A county is an important part of the state's administrative structure and is responsible for providing essential services to its residents. It is also a geographic area that is used for legal and political purposes, such as voting and taxation.