" Green Infrastructure is the sub-regional network of pro-
tected sites, nature reserves, greenspaces, and greenway
linkages. The linkages include river corridors and flood plains,
migration routes and features of the landscape, which are of
importance as wildlife corridors.
Green infrastructure should provide for multi-functional
uses i.e., wildlife, recreational and cultural experience, as well
as delivering ecological services, such as flood protection
and microclimate control. It should also operate at all spatial
scales from urban centres through to open countryside.

Conservation Fund	At The Conservation Fund, we see green infrastructure as a network of natural areas and open spaces—such as woodlands, wetlands, trails and parks—that conserves ecosystems, helps sustain clean air and water and provides many other benefits to people and wildlife.
US EPA	"Green infrastructure is an approach to wet weather management that is cost-effective, sustainable, and environmentally friendly. Green Infrastructure management approaches and technologies infiltrate, evapotranspire, capture and reuse stormwater to maintain or restore natural hydrologies." and in glossary..."An adaptable term used to describe an array of products, technologies, and practices that use natural systems – or engineered systems that mimic natural processes – to enhance overall environmental quality and provide utility services. As a general principal, Green Infrastructure techniques use soils and vegetation to infiltrate, evapotranspirate, and/or recycle stormwater runoff. When used as components of a stormwater management system, Green Infrastructure practices such as green roofs, porous pavement, rain gardens, and vegetated swales can produce a variety of environmental benefits. In addition to effectively retaining and infiltrating rainfall, these technologies can simultaneously help filter air pollutants, reduce energy demands, mitigate urban heat islands, and sequester carbon while also providing communities with aesthetic and natural resource benefits."
American Society of Landscape Architects	"Green infrastructurecan be considered aconceptual framework for understanding the 'valuable services nature provides thehuman environment.' At the national or regional level, interconnected networks of park systems and wildlife corridors preserve ecological function and create a balance between built and natural environments. At the urban level, parks and urban forestry are central to reducing energy usage costs and creating clean, temperate air. Lastly, green roofs, walls, and other techniqueswithin or on buildings bring a range of benefits, includingreduced energy consumption and dramatically decreasedstormwater runoff. At all scales, green infrastructure provides real ecological, economic, and social benefits."
US Conference of Mayors	"The US Conference of Mayors defines green infrastructure as the interconnected network of open spaces and natural areas, such as greenways, wetlands, parks, forest preserves and native plant vegetation, that provide wildlife habitat, natural drainage, recreational opportunities and help to sustain our Nation’s cities..."
Environmental Council of States	"green infrastructure is a cost effective and environmentally friendly approach to mitigating sewer overflows and works by diverting stormwater from the sewer system and directing it to areas where it can be infiltrated, evapotranspirated or re-used..."
University of Melbourne Green Infrastructure Research Group	"Green Infrastructure is the network of designed and natural vegetation found in our cities and towns. It includes public parks, recreation areas, remnant vegetation, residential gardens and street trees as well as innovative and emerging new urban greening technologies such as green roofs and green walls."
Natural England, UK	‘Green Infrastructure is a strategically planned and delivered network comprising the broadest range of high quality green spaces and other environmental features. It should be designed and managed as a multifunctional resource capable of delivering those ecological services and quality of life benefi ts required by the communities it serves and needed to underpin sustainability. Its design and management should also respect and enhance the character and distinctiveness of an area with regard to habitats and landscape types. Green Infrastructure includes established green spaces and new sites and should thread through and surround the built environment and connect the urban area to its wider rural hinterland. Consequently it needs to be delivered at all spatial scales from sub-regional to local neighbourhood levels, accommodating both accessible natural green spaces within local communities and often much larger sites in the urban fringe and wider countryside.’
Town and Country Planning Association, UK	Green Infrastructure is the sub-regional network of protected sites, nature reserves, greenspaces, and greenway linkages. The linkages include river corridors and flood plains, migration routes and features of the landscape, which are of importance as wildlife corridors. Green infrastructure should provide for multi-functional uses i.e., wildlife, recreational and cultural experience, as well as delivering ecological services, such as flood protection and microclimate control. It should also operate at all spatial scales from urban centres through to open countryside.