Edible bird's nests are created by swiftlets' solidified saliva, which are harvested for human consumption. They are particularly prized by the Chinese, due to their rarity, exquisite flavor and supposedly high nutritional value, especially for the skin. They are among the most expensive animal products consumed by humans. (Wikipedia)
Bird's nests are typically served as a soup. Dissolved in water, they will have a gelatinous texture. They can also be used as an ingredient in congees, egg tarts and other desserts, or processed into jelly form.
2016: The one I tried in Malacca came in tea form. They had a choice of ginseng tea and winter melon. I had ginseng. It was sweet and the bird's nest jelly didn't have any distinct taste. Priced at RM10 for the small cup, it sure was expensive. I hope my skin looks prettier now.