[djur]

You can dynamically create symbols and expect them to be garbage collected as of Ruby 2.2. They only become "immortal" if you use them to define a method, instance variable, or constant. So the common use case of hash keys is fine. One important advantage of symbols versus strings is that Symbol#== is constant time.

[inferiorhuman]

Ah hah, you've discovered how long it's been since I've thought about Ruby performance.

  One important advantage of symbols versus strings is that Symbol#== is constant time.

At that point though why not use integer constants?

[knodi123]

syntactic sugar- you don't have to pre-declare them or worry about conflicting values. And occasionally the symbol.to_s method is useful in logging or whatnot. That's pretty much it.