An enum, short for enumeration, is a custom data type that allows you to define a type by enumerating (listing out one-by-one) all of its possible variants. In Rust, if something is one of a given set of possibilities (e.g., Rock or Paper or Scissors), it's probably appropriate to represent that data with an enum, like so: enum RpsChoice { Rock, Paper, Scissors }.
An instance of an enum can be one and only one of the enum's declared variants at any given time. Unlike enumerations in some other languages, variants in Rust are not restricted to a singular data type. When you define an enum, you can decide for each of its possible variants whether or not that variant will hold additional embedded data; each variant of the enum is also allowed to hold data of completely different types and amounts.
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