Bit.ly is a URL shortening service that allows users to customize the identifier for more memorable and appealing links, as demonstrated by creating a short link for ntalbot’s WeatherBot rock-paper-scissors script. This service not only helps make URLs more attractive but also provides tracking of click-through rates, offering users insights into the popularity of their shared links. Chris Wanstrath, also known by the handle @defunkt, highlights these features and notes an update regarding a link fix.