A county is a territorial division of the State for administrative purposes.

Most of the eastern states and parts of the western states were divided into counties in the 19th century and later further subdivided into parishes. They have no political funtion - their only purpose was for the registration of land ownership.

This Wikipedia page enables you to click on the link of each county which gives a map with the location of the relevant county in NSW and any additional information (origin of name, parishes etc) which might be of interest.