Subject headings are a formalized way of of searching library catalogs. The right subect heading can help you get to information more quickly.
For example, Urban Planning can be described using the following terms:
You could search the library catalog for all those keywords. Or, use one subject heading to find relevant library materials about planning:
Who determines subject headings? The Library of Congress. Copies of the complete set of the Library of Congress Subject Headings are available at the Reference Desk.
Sometimes browsing the library stacks can help you find books you didn't even know you were looking for. The following are good areas to peruse.
HE 305-311: Urban transportation.
HM 756-781: Community.
HN 41-46: Community centers. Social centers.
HT 101-395: Urban groups. The city. Urban sociology.
HT 161-165: Garden cities. "The city beautiful."
HT165.5-169.9: City planning.
HT-170-178: City population.
HT 231: Effect of city life.
HT 321-325: The city as an economic factor, city promotion.
HT330-334: Metropolitan areas.
HT 351-352: Suburban cities and towns.
HT 361-384: Urbanization. City and country.
HT 388: Regional economics. Space in economics.
HT 390-395: Regional planning
NA 1-9428: Architecture
NA 9000-9048: Aesthetics of cities. City planning and beautifying
Maps of the library are available at the 2nd floor Reference Desk, elevator lobbies, and also online.