Community gardens provide access to fresh produce and plants as well as access to satisfying labor, neighborhood improvement, sense of community and connection to the environment. They are publicly functioning in terms of ownership, access, and management, as well as typically owned in trust by local governments or not for profit associations.

A city’s community gardens can be as diverse as its communities of gardeners. Some choose to solely grow flowers, others are nurtured communally and their bounty shared, some have individual plots for personal use, while others are equipped with raised beds for disabled gardeners.

Climate change is threatening food security. Climate change is expected to cause a global decline in agricultural output, making fresh produce increasingly unaffordable. Community gardens encourage an urban community's food security, allowing citizens to grow their own food or for others to donate what they have grown. Peak oil is particularly relevant where food production relies heavily on fossil fuels. Community garden advocates point out that locally grown food decreases a community's reliance on fossil fuels for transport of food from large agricultural areas. It also decreases the level of fossil fuels used in agricultural machinery, since more of the work is done manually.

Community gardens improve users’ health through increased fresh vegetable consumption and providing an outlet for exercise. The gardens also combat two forms of alienation that plague modern urban life, by bringing urban gardeners closer in touch with the source of their food, and by breaking down isolation by creating a social community. Community gardens provide other social benefits, such as the sharing of food production knowledge with the wider community and safer living spaces. It has been found that active communities experience less crime and vandalism.

Community gardens involve a change in food systems in order to change food production.

Unlike public parks, whether community gardens are open to the general public is dependent upon the lease agreements with the management body of the park and the community garden membership. Open or closed gate policies vary from garden to garden. There is no 'off the shelf model' of a community garden, however; they provide a green space in urban areas, along with opportunities for social gatherings, beautification, education and recreation. However, in a key difference, community gardens are managed and maintained with the active participation of the gardeners themselves, rather than tended only by a professional staff. A second difference is food production: Unlike parks, where plantings are ornamental (or more recently ecological), community gardens often encourage food production by providing gardeners a place to grow vegetables and other crops. To facilitate this, a community garden may be divided into individual plots or tended in a communal fashion, depending on the size and quality of a garden and the members involved.

As discussed below, "community garden" is the term favored in the United States, Canada, Australia and New Zealand. One source and clearinghouse on community gardening information in North America is The American Community Gardening Association, a non-profit membership organisation. Research is forming as to whether or not Community Gardening dictates a connotation with social change in the U.S.A. and how changing this term may benefit the effort to involve entire communities.

Community gardens vary widely throughout the world. In North America, community gardens range from familiar "victory garden" areas where people grow small plots of vegetables, to large "greening" projects to preserve natural areas, to tiny street beautification planters on urban street corners. In the UK and the rest of Europe, closely related "allotment gardens" can have dozens of plots, each measuring hundreds of square meters and rented by the same family for generations. In the developing world, commonly held land for small gardens is a familiar part of the landscape, even in urban areas, where they may function as mini-truck farms.[citation needed]

For all their diversity, however, most community gardens share at least four elements in common:[citation needed]

In many ways community gardens are re-enforcing basic human instincts that are slowly deteriorating due to the convenience of modern life (http://www.kens5.com/video/featured-videos/Micro-gardens-help-poor-learn-to-supplement-food-91546344.html)