scan method without a block of code returns an array of all the matching parts of the string:
puts "This is a test".scan(/\w/).join(',')
First you define a string literal, then you scan over it for alphanumeric characters using /\w/.
Finally you join the elements of the returned array together with commas.
split method splits a string into an array of strings on the periods:
puts "this. is. a. test.".split(/\./).inspect
If you'd used . in the regular expression rather than \., you'd be splitting on every character rather than on full stops.
. represents "any character" in a regular expression.
To escape it by prefixing it with a backslash.
inspect method is common to almost all built-in classes in Ruby and it gives you a textual representation of the object.
split can split on newlines, or multiple characters at once, to get a cleaner result:
puts "this is a test".split(/\s+/).inspect