Consistent hash rings are beautiful structures, yet often poorly explained. Implementations tend to focus on clever language-specific tricks, and theoretical approaches insist on befuddling it with math and tangents irrelevant.
This is an attempt at explanation – and a Python implementation – accessible to an ordinary high-schooler.
Fairly often, you need a way to take an item and get back another stored item. For instance, you may want to take a URL and get back the server the website is hosted on.
These cases can be accomplished by a map, which effectively acts like a phonebook – you look up names (or keys), and you get back information (or values) about the name.
A glossary, too, is a map – given a word, it can take you to the exact page the word is referenced.
All a map is is a way to take something that can point to another item, and then return that second item.
Computers can pull this trick off too: they take a value, and store it at a location in memory. Then, given a key, they somehow use that key to figure out the address of that memory location, go to that location, and return that value.