Meta’s new Threads app, billed as a kinder alternative to other microblogging services, surpassed 100 million users in days, making it the fastest-growing consumer app ever. It’s easy to join (see a how-to guide with a list of features, and how to find the accounts you follow) although some recommend waiting, particularly due to privacy concerns. (See details about what information it collects, as well as the privacy policies of similar services.) The initial surge may not be enough to capture Twitter’s user base.