There has been an explosion of community gardens in America, popping up behind churches, schools, in parks, next to city 
halls, and even on corporate campuses. As the name suggests, these are gardens that are shared by many users. Most often, the garden is a plot of land that is broken up into multiple gardens, each of which is maintained by an individual. In the United states, gardens are generally between 10’x10’ and 20’x20’.
There is a strong tradition of community gardens in urban areas, often involving vacant lots that have been cleared and turned into gardens. Many times, these are developed without official permission, and can be in danger of being removed if the land is sold or otherwise reclaimed. More and more, we are seeing these gardens in suburban areas, where public or private landowners offer unused land for gardens. Cities will often turn part of a park or the grounds of a city building (a school, for example) into a community garden. Likewise, companies with large campuses offer gardens to employees and the surrounding community. The community benefits from the gardens, while the owner benefits by no longer having to maintain the land.
The organization of community gardens varies widely, from anarchy to strict rules. Some gardens are impromptu and open to all on a first-come, first-served model with no leadership. Others have locked gates and years-long waiting lists for plots, especially in more affluent urban areas where land is at a premium. Most gardens are somewhere in-between, with formal (though almost always volunteer) leadership, and a sign-up process for plots. Many are run by churches or other non-profits who oversee the gardens and will charge a small fee for shared expenses, such as water, fencing, and administration, each year.
Community gardens offer many benefits, with a few drawbacks. For apartment-dwellers and those without room for gardens on their property, the advantages are obvious, but some choose a community garden even when they have room for one in their backyard. There is a sense of camaraderie in a community garden, and the expertise of other gardeners can be invaluable, especially to those just learning. A community garden can be an excellent way to get into gardening, since the plots are almost always well-established and are unlikely to require extensive conditioning for a successful growing season. Gardeners often share their tools, especially specialty tools that are rarely used, a benefit for beginners and veterans alike. It’s also a lot easier to trade some of an over-abundant zucchini crop for some of another gardener’s tomatoes when you’re gardening side-by-side.
This does not mean there are no disadvantages. Your plot will likely be open to the public and will not be under your direct control. This can lead to a “tragedy of the commons” where visitors or fellow gardeners do not respect your property, although this is a rare thing. It can also be a pain to have to haul all of your gardening supplies to the community garden, instead of just pulling them out of your garage or shed. Some less-established gardens will lack water, making gardeners dependent on rain or whatever water they can haul to the site or catch in a rain barrel. Most of these are minor concerns when compared to the benefits, and are generally easily overcome.
If you’re interested in participating in a community garden, odds are there’s one near you. The American Community Gardening Association (http://www.communitygarden.org) is an excellent resource and even has a community garden finder on its website (http://acga.localharvest.org/), which lists 200 community gardens in Ohio.
