A dictionary is a data structure in Python that stores key-value pairs, where each key is associated with a value. A dictionary is created by enclosing the key-value pairs in curly braces and separating them by commas. A dictionary can be accessed by using the keys as indexes or by using methods such as keys(), values(), or items(). In the code, systems is a dictionary that has four key-value pairs, each representing an IP address and its corresponding operating system. A tuple is a data structure in Python that stores an ordered sequence of immutable values, enclosed in parentheses and separated by commas. A tree is a data structure that consists of nodes connected by edges, forming a hierarchical structure with a root node and leaf nodes. An array is a data structure that stores a collection of elements of the same type in a contiguous memory location.