It originated organically on Twitter as early users wrote “at” each other. Following that Twitter formally adopted it, and Mastodon imitated Twitter. https://e

It originated organically on Twitter as early users wrote “at” each other. Following that Twitter formally adopted it, and Mastodon imitated Twitter. https://en.wikipedia.org/wiki/Mention_(blogging)#@_(at_sign) https://en.wikipedia.org/wiki/Mention_(blogging)#@_(at_sign) Within Mastodon’s UI usernames are typically displayed as just e.g. @breaking, avoiding the visual noise of multiple at signs.