Hashtag Symbol Meaning — Symbolism, Origins & Significance

The # symbol has lived several genuinely distinct lives, and knowing which one you're talking about matters: it started as a symbol for weight measurement ('pounds'), was formally christened the 'octothorpe' by Bell Labs engineers designing telephone keypads in the 1960s, and only became 'the hashtag' — with its now-familiar function of marking and grouping topics on social media — through a specific, dated, documented proposal by one Twitter user in 2007, an origin considerably more recent and traceable than most people assume.

This page walks through all three chapters honestly and in order: the symbol's older use in weights and typography, the deliberate 1960s engineering decision that gave it the name 'octothorpe,' and the real 2007 story of how a single suggested tweet turned an obscure keyboard symbol into one of the defining pieces of social media grammar, used now by billions of people who mostly have no idea it was ever called anything else.

What the Hashtag Symbol Represents

Before it meant anything to do with social media, # had a long-standing, fairly mundane function primarily tied to numbers and measurement in English-language usage, most commonly as an abbreviation for 'pound' or 'number' — '#5' meaning either 'number 5' or 'five pounds' depending on context, a dual usage with genuinely ambiguous roots that reflects the symbol's own somewhat unclear typographic history, generally traced back to variant forms of the Latin abbreviation 'lb' (for libra, the Roman unit of weight) written with a horizontal line through it in certain handwritten and typeset traditions, though, similar to the @ symbol's origin, the exact lineage isn't fully settled with total scholarly certainty.

The symbol received its distinctive, deliberately invented formal name, 'octothorpe,' in a specific and reasonably well-documented mid-twentieth-century engineering context: Bell Labs engineers working on the design of touch-tone telephone keypads in the 1960s needed the symbol for use as a functional key on the new keypad layout (the now-familiar '#' and '*' keys, still present on most phone keypads and used for various telecommunications and automated-system functions), and 'octothorpe' was coined internally, apparently as something of a playful, semi-informal engineering-team invention — 'octo' referencing the symbol's eight points or terminal endpoints, with the 'thorpe' portion of the name having several competing, not entirely certain explanations offered over the years (including, among various origin stories that have circulated, a joking reference to the athlete Jim Thorpe), a genuinely uncertain and somewhat playful bit of etymology compared to the more straightforwardly documented history of the symbol's other uses.

The symbol's transformation into 'the hashtag,' with its now globally familiar function of marking and grouping related social media content under a shared searchable topic label, happened considerably later and is unusually precisely dated for a piece of modern digital culture: Chris Messina, an early user and product designer within the developing Twitter platform and broader open-source and web technology community, proposed in a tweet on August 23, 2007, that Twitter users adopt the # symbol followed by a keyword as a way of grouping related tweets around shared topics, drawing explicitly on the symbol's prior use in Internet Relay Chat (IRC), an older text-based online chat protocol where # was already used, in a related but distinct way, to denote and label specific chat channels or 'rooms' users could join around a shared topic — meaning Messina's 2007 proposal wasn't inventing an entirely new use from nothing, but adapting an existing piece of established online-community convention from IRC into the newer, considerably larger Twitter platform, where it then spread explosively and was subsequently adopted, in one form or another, across essentially every major social media platform that followed.

Historical Origins

The # symbol's typographic history before its digital-era transformations is somewhat murkier and less precisely documented than either the @ symbol's or the modern hashtag's own more recent history, but the most widely accepted account traces it to variant handwritten and typeset forms of the abbreviation 'lb' (for the Latin libra, meaning pound weight), written in various historical printing and handwriting traditions with a horizontal line struck through the letters as a standard abbreviation-marking convention, which over successive generations of copying and simplification gradually evolved visually into the now-familiar crosshatch symbol, losing any direct visual resemblance to the original letters 'lb' along the way — a case, similar to the ampersand's own well-documented gradual ligature evolution from the Latin 'et,' of a symbol's shape drifting very substantially from its textual origin through repeated simplification over an extended period.

The symbol's formal name, 'octothorpe,' was coined specifically within Bell Labs' engineering context during the development of touch-tone telephone keypad technology through the 1960s, needed as a functional, nameable key on the newly designed keypad alongside the numeric digits and the asterisk key, both of which required functional roles within the emerging touch-tone dialing and automated telephone system technology of the period. While the precise, fully agreed details of exactly who coined the name and the exact reasoning behind its more unusual second half remain genuinely a little uncertain and have been recounted with some variation across different retellings by people involved, the 'octo-' prefix's reference to the symbol's eight endpoints is consistently agreed upon across the various accounts, and the name did become the established formal engineering and telecommunications-industry term for the symbol from this period onward, used in technical documentation and telecommunications contexts even though it never gained much traction in everyday popular usage outside those specific professional circles.

The hashtag's specific social-media transformation is, by contrast, unusually precisely documented: Chris Messina's August 23, 2007 tweet explicitly proposing the # convention for Twitter is a matter of clear public record, and Messina has spoken publicly on multiple occasions about drawing the idea directly from Internet Relay Chat's pre-existing use of # to label and organise topic-based chat channels, a convention with its own roots reaching back to IRC's early development in the late 1980s. Twitter itself did not immediately or officially implement hashtags as a built-in, clickable, searchable platform feature — that came somewhat later, through gradual informal adoption by users followed by Twitter's own subsequent official platform support for hashtag functionality — but the specific dated 2007 proposal is nonetheless treated, including by Messina himself and by subsequent tech journalism and internet-history writing, as the clear and well-documented origin point of the hashtag as a distinct, named social media convention, a genuinely unusual case of a now near-universal piece of digital communication grammar being traceable to one specific, dated, publicly recorded proposal by one identifiable individual.

Cultural Variations