I recently stumbled across an algorithm called HyperLogLog++, which can be used to efficiently estimate the number of unique elements in large sets. This project attempts to estimate the number of unique usernames that have visited this project. Back when cloud variables had no length limit, this was as easy as creating a cloud list and storing the username of every unique viewer. However, it was not space efficient and is no longer possible. Credits: https://storage.googleapis.com/pub-tools-public-publication-data/pdf/40671.pdf
