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human
ELI5: What makes eggs so essential to a lot of baking recipes?
gpt
Eggs have lots of functionality in baking. 

One of the main functions in many recipes calling for eggs is to add structure to the product. Eggs contain lots of proteins wich will coagulate once they reach a certain temperature. Once the proteins "set" they hold their shape therefore adding structure to cakes or thickening custards for example. 

These same proteins are responsible for egg's ability to hold air bubbles when whipped. When you whip egg whites into a foam thousands of tiny air bubbles are trapped by the proteins. These bubbles make the finished product more light and airy. The most pure example of this is a meringue. 

Eggs also act as an emulsifier when mixed with two ingredients that have a hard time staying well mixed on their own. This adds to the overall texture and makes the product more stable. 

Eggs also have some other more minor (but still important) functions
as well. Eggs yolks are a good source of fat which adds richness and creaminess to many products. Eggs contain a lot of water which contributes to keeping the baked good moist. Eggs also add flavor and important nutritional content to the foods they are in as well. Finally, eggs add color to baked goods, most noticeably when egg-wash is brushed on top of a product before baking, this will add sheen and allow for a darker finish.

Hope this helps!