Meta CEO Mark Zuckerberg recently shared the email address he used to create his first Facebook account, mzuckerb@fas.harvard.edu, during a nostalgic exchange on Threads. This revelation was sparked by an artist's post referencing how .edu email addresses were required to join Facebook in its early days. Despite common belief, Zuckerberg was not the first to have a Facebook ID; three testing accounts were created and later deleted before his, making him the fourth official user. His co-founders, Chris Hughes and Dustin Moskovitz, followed as the fifth and sixth users. The post resonated with many users, leading to a wave of nostalgic comments reminiscing about their own experiences of joining Facebook. Facebook launched in 2004 as a directory for college students and has since evolved into a leading social media platform.