Enumerated data types, commonly known as enums, are user-defined types that consist of a collection of named values. They enhance code readability and self-explanatory nature by providing descriptive names for values that could otherwise be represented by arbitrary numbers or strings.

More specifically, enumerated data types allow programmers to create a new type within a programming language that comprises a set of named values, referred to as enumerators or enum members. The primary advantage of using enumerated data types is that they facilitate easier understanding and maintenance of programs by assigning meaningful names to values.

For instance, consider a program that manages the days of the week. Without enums, you might represent each day with a number from $1$ to $7$. While this approach works, it can lead to confusion, as the meaning of each number is not immediately clear. By utilizing an enumerated data type, you can assign each day a specific name, such as $MONDAY$, $TUESDAY$, and so forth. This improves the readability and clarity of the code significantly.

Moreover, enumerated data types play a crucial role in error prevention. When a function expects an argument of an enumerated type, it will only accept values that fall within the defined set. This feature is particularly beneficial for identifying mistakes and bugs. For example, if you mistakenly pass the number $8$ to a function that expects a day of the week, the compiler will generate an error, as $8$ is not a valid enumerated value.

Additionally, enumerated data types can represent a collection of related constants within a program. For example, you might define an enum to represent the various states of a game, such as $START$, $PLAYING$, $PAUSED$, and $GAME\_OVER$, or to depict different user roles in a system, such as $ADMIN$, $USER$, and $GUEST$.

In conclusion, enumerated data types are a powerful feature in programming that enhances code readability, helps prevent errors, and allows for the representation of related constants. They are widely utilized across many programming languages, including C++, Java, and Python.