is actually an ordered map. A map is a type that associates values to keys.” – http://php.net/manual/en/language.types.array.php Python dictionaries “Unlike sequences, which are indexed by a range of numbers, dictionaries are indexed by keys, which can be any immutable type; strings and numbers can always be keys. […] It is best to think of a dictionary as an unordered set of key: value pairs, with the requirement that the keys are unique (within one dictionary).” – http://docs.python.org/2/tutorial/datastructures.html