The term "building setback" means the required separation between a lot line (and/or right-of-way line) and a building or structure. Setbacks vary by zoning district, and there are numerous exceptions to accommodate a variety of particular lot circumstances.  Setbacks also vary by type of structure.  Detached accesory buildings have different setback requirements than dwellings. 

Setback compliance is a necessary consideration for any construction project, therefore the precise location of property lines should be ascertained early in the design process.