Especially in the past, eggs represented a very important resource for cooking, particularly in the countryside. Although there are different types, the most consumed ones are chicken and a characteristic of the latter is their notable protein content, which is why they are often used to replace meat.
Use in cooking
Eggs can be cooked in many different ways (cooked, raw, beaten) and, furthermore, they can be used for a large number of preparations as a fundamental ingredient.
Preservation
To make sure you consume a fresh egg, the best empirical test to do is to immerse it in a saucepan of cold water: if it sinks to the bottom, it would mean that it is still easily edible.
Curiosity
Eggs are usually used as a meat substitute, especially on less rich tables, as they contain a large quantity of proteins.