Advent of Code is an annual Advent calendar of small programming puzzles that can be solved in any programming language. One programming puzzle a day is released from 1st to 25th December, divided in two parts (the second of which is unlocked after solving the first). Advent of Code is created by Eric Wastl, and is 100% free. If you like Advent Of Code and want to support its creator, you can donate to him here. If you want to hang out with other fellow coders, discuss about puzzles and solutions, or just have a look around, you can join the official subreddit: aoc-reddit