hash = { "key1" => "value1", "key2" => "value2" } # same as objects in JavaScript
hash = { key1: "value1", key2: "value2" } # the same hash using symbols instead of strings
my_hash = Hash.new # same as my_hash = {} – set a new key like so: pets["Stevie"] = "cat"
pets["key1"] # value1
pets["Stevie"] # cat
my_hash = Hash.new("default value")
hash.select{ |key, value| value > 3 } # selects all keys in hash that have a value greater than 3
hash.each_key { |k| print k, " " } # ==> key1 key2
hash.each_value { |v| print v } # ==> value1value2
my_hash.each_value { |v| print v, " " }
# ==> 1 2 3