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Ruby variables don't need declarations or types. Just assign:

name = "Alice"
age = 30
active = true
nothing = nil

The casing of the first character determines the kind of variable:

• name — local variable
• @name — instance variable
• @@name — class variable
• $name — global
• Name — constant (by convention)

Symbols are interned identifiers — like strings, but with one distinguishing feature: there's only one copy of each in memory. Use them for fixed-string keys in hashes or to name things:

status = :active
user = { name: "Alice", age: 30 }   # symbol keys

Symbols are hashable, fast to compare, and immutable.