What is the internal structure of a Ruby symbol and why are symbols faster than strings?

Symbols are immutable, interned identifiers stored once in a global symbol table.

Symbols in CRuby are stored in an internal symbol table and referenced via unique IDs. Unlike strings, symbols are not duplicated in memory and are immutable. This allows fast pointer comparison instead of full string comparison. Modern Ruby also allows GC of dynamically created symbols, but core symbols remain interned.