A township is a division of a county in many states. A survey township is simply a geographic division for land records. A civil township, which may or may not be coextensive with a survey township, is a form of local government below the county level.
The scope of township government, in states that have such a thing, depends on the law of each state. Township governments are found primarily in the Northeast and Midwest.
In some states, such as New York, Wisconsin, and the New England states, a township is called a town, not to be confused with entities called towns in other states.