If you want more options, simply expand the list: cat | dog | mouse | fish. If you want to search for the literal text cat or dog, separate both options with a vertical bar or pipe symbol: cat | dog. You can use alternation to match a single regular expression out of several possible regular expressions.
I already explained how you can use character classes to match a single character out of several possible characters. Alternation with The Vertical Bar or Pipe Symbol
