Zoning is a restriction on the way that land can be used. It allows governments to control the development of communities and ensure they are functional and safe places. Without zoning, a gun store could open up next to a school, an adult club next to a playground, and a busy store on your residential street. Zoning prevents these things from happening and by doing so, it protects property values and ensures communities work in an orderly fashion.
The government- usually a local municipality, town or township- sets the zoning rules and regulations for any given area. There may be a number of different classifications set up under these zoning laws. For example, an area may be zoned "residential." There are also different types of residential zoning: some residential zones allow for single family homes, while others allow for apartments and townhouses or mixed housing. Other examples of broad categories under zoning laws include areas zoned "commercial", for businesses, or "agricultural", which would allow property owners to have livestock.
When you use a piece of land or property, you must comply with the zoning rules. If you buy a house, for example, you can't just move your pet goats and llamas in - unless that house is in an area zoned for that, like an agricultural zone. If you do wish to do something that doesn't comply with the stated requirements of the zoning laws for that piece of property, you'd need to get an exception (often called a special use permit) by applying for one and, usually, by getting the approval of your neighbors and the town as well.
Sometimes zoning of a given area can also change. In such instances, those who owned property before the change took place are generally "grandfathered" in and allowed to keep using the property for the purpose they have always used it for, even if that use doesn't comply with the new zoning rules.
For details about the zoning requirements in your area, consult with a property lawyer today.