A glossary of definitions for terms relating to biodiversity, ecosystems services and conservation.
All definitions are referenced, where possible preference has been given to internationally recognised definitions (for example those defined by international conventions or agreements). The terms have been chosen to support understanding of biodiversity and conservation issues, and terms relating to biodiversity loss are complemented by those relating to conservation responses supported by international conservation organisations, governments, scientists and business sectors.
More detailed explanations are provided for a number of key terms, to provide further background information.
The terms can be filtered by category to aid in the navigation of the many definitions.
A consequence of an action that affects someone other than the agent undertaking that action, and for which the agent is neither compensated nor penalized. Externalities arise when an individual, a firm or a country takes an action but does not bear all the costs (negative externality) or all the benefits (positive externality) of the action.