Snapchat uses linked-listed to keep track of who you're going to send a snap to. Internet routers use queues to create a buffer of packets that have yet to be

Snapchat uses linked-listed to keep track of who you're going to send a snap to. Internet routers use queues to create a buffer of packets that have yet to be processed. Postgres uses trees or hashes to create table indices for faster queries. Medium uses Bloom Filters to check if a user has read an article or not.