In land-use planning, urban green spaces are open-space areas reserved for parks and other spaces of greenery. These include plant life, water features – also known as blue spaces – and other kinds of natural environments. Most urban open spaces are green spaces, though some may consist of other types of open areas. The landscape of urban open spaces can range from playing fields and other highly maintained environments to more natural landscapes that appear less managed.

Urban green spaces may also include areas that are not publicly accessible, such as privately owned higher education campuses, school sports fields, allotments, neighborhood or community parks and gardens, and corporate campuses. Areas outside city boundaries, such as state and national parks or rural open spaces, are not generally considered urban open spaces. Boulevards, piazzas, plazas, and urban squares are not consistently classified as urban open spaces in land-use planning.

Urban greening policies help revitalize communities, reduce financial burdens on healthcare, and improve quality of life. By promoting the development of parks, green roofs, and community gardens, these policies contribute to cleaner air, mitigate urban heat effects, and create spaces for recreation and social interaction. Most policies focus on community benefits and reducing negative effects of urban development, such as surface runoff and the urban heat island effect. Historically, access to urban green space has favored wealthier and more privileged communities. Recent urban greening has increasingly focused on environmental justice concerns and community engagement in the greening process. In particular, in cities with economic decline, such as in the Rust Belt in the United States, urban greening has broad community revitalization impacts. Urban green spaces have been shown to have a wide-reaching positive impact on the health of individuals and communities near said green space.

The World Health Organization (WHO) defined urban green spaces as "all urban land covered by vegetation of any kind". In academic literature, "urban open space" or "open space" is often used to describe a broader range of open areas. One extensive definition describes open space as follows:

"Thus open space, very simply, is unclosed space. As the counterpart to development, urban open space is a natural and cultural resource, synonymous with neither "unused land" nor "park and recreation areas." Open space is land and/or water area with its surface open to the sky, consciously acquired or publicly regulated to serve conservation and urban shaping functions in addition to providing recreational opportunities.

In almost all instances, the terms urban green space or urban open and green space refer to open areas that reflect natural areas surrounding the city.

Public spaces are broadly construed, including meeting or gathering places that exist outside the home and workplace. These foster resident interaction and opportunities for contact and proximity. This definition implies a higher level of community interaction and places a focus on public involvement rather than public ownership or stewardship.

The benefits that urban open spaces provide to citizens can be categorized into four basic forms: recreation, ecology, aesthetic value, and positive health impacts. Psychological research shows that benefits to visitors of urban green spaces increased with their biodiversity, indicating that "green" alone is not sufficient: the quality and variety of the urban green space are important as well.^{[improper synthesis?]}