The history of the # symbol, commonly known as the hashtag, pound sign, or number sign, is a journey from ancient Roman units of measurement to modern digital culture.
1. Ancient Origins: The Roman Libra
The symbol’s roots trace back to the Roman term libra pondo, meaning “pound weight”.
- The Abbreviation: Scribes used the abbreviation lb for libra.
- The Ligature: Over time, writers added a horizontal bar (a “tilde”) across the top of the letters to indicate it was a single unit. This shorthand evolved into the # shape as the letters were written faster and became stylized.Â
2. Pre-Digital Usage
Before it reached computer screens, the symbol served several distinct purposes:
- Pound/Number Sign: In the U.S., it was traditionally used after a number to indicate weight (e.g., 5#) or before a number to mean “number” (e.g., #1).
- Music: It is often confused with the sharp symbol (♯), which indicates a note should be played a semitone higher, though they are technically different characters.
- Proofreading: Editors once used it to indicate where a space should be inserted between lines of text.
3. The “Octothorpe” and the Telephone
In the 1960s, engineers at Bell Labs added the symbol to telephone keypads to facilitate automated services.Â
- The Name: An employee, Don MacPherson, reportedly coined the name “octothorpe”. The “octo” refers to its eight points, while “thorpe” may have been a tribute to athlete Jim Thorpe or simply a nonsense word used to make it sound official. YouTube +4
4. Modern Era: The Hashtag
The symbol’s most significant cultural shift occurred in 2007 when Chris Messina, a product designer, suggested using # on Twitter (now X) to group related messages.
- The First Hashtag: Messina’s first use was #barcamp, intended as a way to track discussions during a technology unconference.
- Global Adoption: It has since become a universal tool for organizing social media content, sparking social movements (e.g., #BlackLivesMatter, #MeToo), and facilitating marketing campaigns. Time Magazine +4
