Greensgrow Farm, a thriving urban farm in Philadelphia, does a wonderful job describing urban farming on its website. Note that urban farming is one part of the urban agriculture puzzle, not the whole thing itself. Other urban ag endeavors that are distinct from urban farming include community gardens and subsistence urban gardens. Greensgrow’s stellar description of urban farming can be found here: http://www.greensgrow.org/urban-farm/what-is-urban-farming/.
PBS Video: Urban Farming
This is a 25 minute PBS video that explains and examines urban farming in great detail. Check it out to learn more about what individuals are doing to employ rooftop space, urban beekeepers, and vacant lots in their urban farming projects. Linked here: http://video.pbs.org/video/2276862085/.