Edible bird's nests ("EBN") are nests that are made from the saliva strands of Swiftlets. Among the many swiftlet species, only a few are notable to produce EBN from secreted saliva during breeding seasons. In particular, white-nest swiftlets (Aerodramus fuciphagus) and black-nest swiftlets (Aerodramus maximus) are considered as premium grade nests as both are formed mainly from the saliva secretion with only very low percentage of other materials such as grass, mud and feathers. The figure below the general types of EBN that can be found in the market.

Source: Protege Associates

EBN are especially prized in the Chinese culture due to its widely known health and medicinal benefits such as moisturising the lung, resolving phlegm, alleviating cough and recuperating from diseases. This has made EBN among some of the most expensive animal products consumed by humans.