In her new book Because Internet, linguist Gretchen McCulloch gives a very interesting explanation of how the hashtag (#) came to be. The symbol emerged as a shorthand scribble for the Latin abbreviation lb, standing for libra pondo, or "pound by weight". These pound signs became associated with numbers, and were later added to early Bell push-button telephones as symbols to complete certain functions over calls. In the late twentieth century, that same sign was used in internet chatrooms to filter images and other content, and shortly after Twitter came out, user @chrismessina called for using the pound sign to group things on the platform. The site didn't comply immediately, but users really liked the idea, so they kept using the symbols until they caved. Hashtags were then picked up by other sites like Pinterest and Instagram, and are now so prevalent that people use the word in real-life conversation.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.