Urban Agriculture is the fastest expanding element of agriculture and as yet is too little recognized.  The most basic definition is the separation of agriculture that takes place in rural areas from that in urban places. Another useful distinction is “same day delivery” which defines urban agriculture as food that is delivered to towns and cities within the same day or morning after, it is harvested or slaughtered. A third is a locally based food system also referred to as "food with the farmer's face", "food from the county" or "farm to school and cafeteria". 
 
Urban agriculture geographically extends from city-center rooftops to suburban vineyards. Some typical urban farms are: backyard chickens, vacant lot and idle land temporary vegetable gardens, forest gardens, fish tanks, community gardens, small livestock (sheep, goats, rabbits, and the 'compact cow'), ornamental plant nurseries, mushroom sheds, vineyards and orchards, and berry patches. 
 
Since World War II urban has changed from city to metropolis to megapolis (over ten million).  We now live in very much lower density urban places and the opportunities for farming the city have vastly increased. 
 
Agricultural technology advances over the past 25 years have increased urban agriculture's yield per square yard and per hour of work. Instruments the size of a pen can measure soil quality, moisture levels, and disease and insect problems. These are plugged into your computer and an efficient work plan is ready in minutes. You can take your laptop to the vineyard and hook it up to the trellis wires for similar information and be informed as to how many kegs and bottles you will need at harvest. 
 
Very big increases in yields were introduced in the 1980s and 1990s by drip irrigation and plastic hoop-houses at a fraction of the cost and operating expense of previous methods.

Urban Agriculture is now a technologically viable and a socially/politically supportable approach to help feed the planet.