A community garden is a piece of land gardened or cultivated by a group of people individually or collectively. Normally in community gardens, the land is divided into individual plots. Each individual gardener is responsible for their own plot, and the yield or production belongs to them. In collective gardens, the piece of land is not divided. A group of people cultivates it together, and the harvest belongs to all participants. Around the world, community gardens exist in various forms; they can be located near neighborhoods or on balconies and rooftops. Its size can vary greatly from one to another. Depending on the location can determine the price of community gardens

Community gardens have experienced three waves of major development in North America. The earliest wave of community gardens development coincided with the Industrial Revolution and rapid urbanization process in Europe and North America; they were then called 'Jardin d'ouvrier' (or workers' garden). The second wave of community garden development happened during the WWI and WWII; they were part of "Liberty Gardens" and "Victory Gardens" respectively. The most recent wave of community garden development happened in the 1970s during the OPEC crisis, results of grassroots movement in quest for available land to combat against food insecurity.

More recently, community gardens have seen a global resurgence. This may be related to several issues faced by the global population in the 21st century, such as ecological crisis, climate change and the new sanitary crisis.^{[clarification needed]} Community gardens contribute to the urban agriculture movement and the requests from citizens for more community gardens has been surging in recent years. Community gardens are also accessible in over 190 + countries/regions

According to Marin Master Gardeners, "a community garden is any piece of land gardened by a group of people, utilizing either individual or shared plots on private or public land". Community gardens provide fresh products and plants as well as contribute to a sense of community and connection to the environment and an opportunity for satisfying labor and neighborhood improvement. 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.

Community gardens vary widely throughout the world. In North America, community gardens range from "victory garden" areas where people grow small plots of vegetables, to large "greening" projects to preserve natural areas, to large parcels where the gardeners produce much more than they can use themselves. Non-profits in many major cities offer assistance to low-income families, children's groups, and community organizations by helping them develop and grow their own gardens. In the UK and the rest of Europe, the similar "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 market gardens.

Community gardens are often used in cities to provide fresh vegetables and fruits in "food deserts", which are urban neighborhoods where grocery stores are rare and residents may rely on processed food from convenience stores, gas stations, and fast-food restaurants.

Some writers have proposed re-framing the concept of "food deserts" as "food apartheid," emphasizing that neighborhoods lacking access to healthy food have been racially oppressed through segregation, redlining, and limited access to land. Some Black, Indigenous, and people of color have supported self-sustaining community gardens, recognizing that their liberation requires access to both land and healthy food.

Community gardens may help alleviate one effect of climate change, which is expected to cause a global decline in agricultural output, making fresh produce increasingly unaffordable. Community gardens are also an increasingly popular method of changing the built environment in order to promote health and wellness in the face of urbanization. The built environment has a wide range of positive and negative effects on the people who work, live, and play in a given area, including a person's chance of developing obesity. 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. Advocates say locally grown food decreases a community's reliance on fossil fuels for transport of food from large agricultural areas and reduces a society's overall use of fossil fuels to drive in agricultural machinery.