City planning is a profession in which planners work to guide the present and future growth of a city by striking a careful balance between residential, commercial, recreational, and institutional needs. A planner makes the best use of a community’s resources, solves current community problems, and protects important physical and geographical landmarks, all while considering how the future needs of a city will fit in. A city planner should be certified by the American Institute of Certified Planners (AICP).
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Here is how Wise Geek defines urban planning.
Urban planning is a mixture of science and art. It encompasses many different disciplines and brings them all under a single umbrella. The simplest definition of urban planning is that it is the organization of all elements of a town or other urban environment. However, when one thinks about all the elements that make up a town, urban planning suddenly seems complicated - and it is.