Symbols & nil

What's a symbol?

Ruby has a type neither Swift nor Python has: the symbol, written with a leading colon — :pending, :small, :confirmed. A symbol is basically a lightweight, immutable name. Think of it as a string that's optimized for being an identifier rather than text you display to a user:

status = :pending
status.class     # Symbol
status == :pending   # true

Two symbols with the same name are always the exact same object in memory — Ruby only ever creates one :pending. Two strings "pending" and "pending" are equal in value but are separate objects. That's the whole reason symbols exist: cheap, fast, unambiguous identity.