Range[]
A Range represents an interval—a set of values with a beginning and an end.
Example Ranges[]
('a'..'e').to_a #=> ["a", "b", "c", "d", "e"]
(1..5).to_a #=> [1, 2, 3, 4, 5]
(-5..-1).to_a #=> [-5, -4, -3, -2, -1]
(-1..-5).to_a #=> []
Another thing to note is that you can use ... to use a range from the start but not including the end ie.
('a'...'d').to_a #=> ["a", "b", "c"]