Symbols are immutable and stored in memory only once, while strings create new objects each time. Rails prefers symbols because:

• Memory efficiency - symbols are stored once
• Performance - faster comparison operations
• Immutability - prevents accidental modification

# Symbol - same object_id
:name.object_id == :name.object_id  # true

# String - different objects
"name".object_id == "name".object_id  # false