Object Lessons is a series of short, beautifully designed books about the hidden lives of ordinary things. Hashtags silence as well as shout. They originate in the quiet of the archive and the breathless suspense of the control room, as well as in the roar of rallies in the streets. The #hashtag is a composite creation, with two separate design histories: one involving the crosshatch symbol and one about the choice of letters after it. Celebration and criticism of hashtag activism rarely addresses the hashtag itself as an object or tries to locate its place in the history of writing for machines. Although hashtags tend to be associated with Silicon Valley invention myths or celebrity power users, the story of the hashtag is much more interesting and surprising, speaking to how we think about naming, identity, and ownership. Object Lessons is published in partnership with an essay series in The Atlantic.