Bird's Nest, also known as Swallow, Swallow Root and Swallow Vegetable, is a nest built by Jin Siyan of Swift Family and many swallows of the same genus with mixed saliva and feathers, which looks like an ingot. The outer wall of the nest is made up of dense filaments with irregular ribs, while the inner wall of the nest is woven into an irregular mesh with filaments, but the root of the bowl is solid with small falling angles at both ends, generally 6-7 cm in diameter and 3-4 cm in depth.

Edible bird's nest is made of another kind of swallow, belonging to Chrysopteridae, and is called "Jin Siyan". Specifically, it refers to the nests made of saliva secreted by some Jin Siyan species of Chrysopteridae and several Jin Siyan species of Swiftlet in Jin Siyan, and then mixed with other substances (such as feathers), rather than the nests made of passerine birds (such as Ru Yan). Among them, Jin Siyan saliva has the highest protein purity and nutritional value.

There are "blood swallows" in the bird's nest. Because Jin Siyan's food contains seaweed and other things, its saliva contains impurities, so it is named HongLing, not because people mistakenly think that it has not completed the bird's nest and stopped vomiting blood. After picking bird's nest, it has to undergo complicated processing such as steaming, soaking, removing impurities, picking hair and drying. Can be made into finished bird's nest, including Yan Yan, Yan tiao, Yan Bing and Yan Si. Swallow cup is a kind of large and high-quality bird's nest, which is made by removing impurities and keeping its original shape, and the price is particularly expensive.

Jin Siyan's lair. Most of them are built on the cliffs of tropical and subtropical islands. Below the cliff are rolling waves and above them are blue sky and white clouds. Jin Siyan began to build a nest in spring. Its mouth can secrete a gelatinous saliva, which is dried by the sea breeze and turned into a translucent yellowish substance, which is the main component of bird's nest. Jin Siyan made a nest with this saliva, slender seaweed, down feathers and soft plant fibers, which is what we call a "bird's nest". Bird's nest is a precious food and a precious medicinal material. It has the effects of tonifying lung and nourishing yin, and is mainly used for treating cough and hemoptysis caused by fatigue. India, Malay Archipelago, Hainan Island and South China Sea Islands are all produced.