What does it mean for a dictionary to be unordered?

A dictionary being unordered means that the items (the key-value pairs) do not have a fixed sequence when they are stored or retrieved. This characteristic allows for the items to be accessed in any sequence when iterating through the dictionary.

In many programming languages, dictionaries use hash tables for storage, which provide efficient access to values based on their associated keys. Since the internal structure does not maintain the order of item entry, retrieving items from a dictionary does not guarantee that they will appear in the order they were added. This flexibility in sequence allows for operations like insertion and deletion to occur without reordering the entire collection.

Understanding this concept is essential, particularly when handling collections of data, to ensure that the desired implementation and behaviors are expected during operations involving dictionaries.