Aesop's Fables are a collection of short stories which are designed to illustrate simple sayings. The original Aesop's Fables originated in Ancient Greece, and over the centuries numerous other stories have been added by authors from a wide range of regions. Many bookstores carry various versions of Aesop's Fables, typically in the children's literature section, and you might be surprised by how many of these fables you are familiar with, along with the number of references to these famous short stories which appear in popular culture.
Aesop himself was supposedly a real person. According to historical evidence, he was a slave in Ancient Greece between 620-560 BCE. Some historians have suggested that Aesop did not actually exist, although he was referenced by contemporaries in Greek society. It is possible that Aesop was actually a collective of people who passed down folk wisdom in the form of brief parables which were collected under one name for publication.
All of the fables are relatively short, and many of them are designed as cautionary tales. Many of them feature anthropomorphized animals, for example the Tortoise and the Hare. Each fable features a situation and a set of actions, and finishes with a brief moral: in the case of the Tortoise and the Hare, the moral is “slow and steady wins the race.” You may also be familiar with the Boy Who Cried Wolf, and the Fox and the Grapes, the inspiration for the saying “sour grapes.”
The simple stories and morals in Aesop's Fables are aimed mostly at children, and as a result collections of these fables are often lavishly illustrated to attract the attention of younger readers. Many people in the Western world have read at least a few of the fables at some point in their lives, and some have internalized the many morals of the books, although they may not realize it. Thanks to Aesop's Fables, people also make references to things like belling the cat, the goose with the golden egg, and the wolf in sheep's clothing, among many other things.
Many printings of Aesop's Fables mix the original Ancient Greek fables in with works by later authors, including modern fables. It is also common to see retellings of the stories in Aesop's Fables in other forms, like longer books, and in some regions they are part of the oral folklore tradition. Coming up with new fables to illustrate morals you think are important for the young people in your life can be a fun exercise.