Enum is a data type consisting of a set of named constants called enumerators. It provides a way to define a collection of related values that can be used in place of literal values, making code more readable and less error-prone.
"I'll create an Enum for the different coffee sizes - tall, grande, and venti - so we don't have to keep using magic strings everywhere like those amateurs over at Starbucks."
"We could use a boolean for the user's account type, but let's future-proof it with an Enum in case marketing comes up with even more ways to segment our users and squeeze out every last penny."
Martin Fowler's Encapsulated Collection: This article discusses the challenges of encapsulating collection fields in objects and various approaches to handle getting and setting of these fields while maintaining encapsulation.
Martin Fowler's Consumer-Driven Contracts: A Service Evolution Pattern: While not directly about Enums, this in-depth article covers designing schemas for backwards and forwards compatibility, including the use of extension points which is a related concept.
Note: the Developer Dictionary is in Beta. Please direct feedback to skye@statsig.com.