Zoning is a term which is used for assigning permitted uses of particular parcels of land by local governments. The 
word itself is largely self-explanatory. Various zones are designated by the local government for various uses of land like residential, commercial, agricultural and industrial. Zoning is also used frequently to designate the various types of buildings which can be raised in a particular area, like maximum height restrictions, high-rises, high density housing, etc.
The essential philosophy behind zoning regulations is to separate various property uses which are incompatible. For example, separating and keeping the residential neighborhoods away from big factories and industries producing smokes. There are numerous instances where exceptions or variances to the zoning rules are possible. For example, you could be granted a small residential variance in an industrial zone for a home to house the night watchman. Variances are usually granted because of some perceived difficulty due to some specific nature of the property in question or to accommodate a unique requirement which is not otherwise against the public interests.
Usually, zoning would be divided into five major categories in urban areas – special (E.g. shopping malls, airports, sports complexes, power plants etc.), industrial, commercial, mixed residential-commercial, and residential. Usually these categories constitute of a number of sub-categories. For example, there could be separate zones for large retail, small-retail, lodging, office use and others within the commercial category, whereas industries could be subdivided into warehouse uses, light assembly and heavy manufacturing.
Zoning laws, of course, are not without their share of misuse or critics. Zoning has been criticized as a means to promote economic and social segregation through exclusion, along with potential property right infringements. Municipalities are able to maintain artificial high housing costs by improper use of various land-use restrictions like the maximum density requirements, increasing the tax base while effectively excluding lower income groups.
To get in-depth details, join expert speaker Carl Stephani in this session where he will give you an understanding of the very simple logic behind the zoning system so that you not only understand the meaning of zoning terminology, but also understand how the different elements of zoning inter-relate and operate in the overall system of zoning as applied in the United States.
