hashtag symbol
About hashtag symbol
# is the hashtag symbol, a versatile character with multiple names and applications across different contexts. The hashtag symbol # is officially known as the NUMBER SIGN in Unicode, but is also commonly called the pound sign (in American English), the hash key, or the octothorpe. The hashtag symbol has become one of the most recognizable characters in the digital age, particularly since its adoption as the hashtag marker on social media platforms like Twitter, Instagram, and TikTok. The hashtag symbol serves as a powerful tool for content categorization, topic discovery, and online community building.
The hashtag symbol # consists of two horizontal lines intersecting two vertical lines, forming a grid pattern of four open spaces. As a Unicode character officially named NUMBER SIGN, the hashtag symbol holds codepoint U+0023 within the basic ASCII set, ensuring universal compatibility across all fonts, operating systems, and digital platforms. The hashtag symbol is located on the standard keyboard above the number 3 key (Shift + 3) on most US keyboards, making it one of the most accessible special characters for quick typing.
【Social Media Revolution】 The hashtag symbol was first proposed for use on Twitter by Chris Messina in 2007 as a way to group conversations on the platform. The idea quickly caught on, and the hashtag symbol became the defining feature of Twitter, later adopted by Instagram, Facebook, LinkedIn, TikTok, and YouTube. Today, clicking or tapping a word or phrase preceded by the hashtag symbol (e.g., #technology, #travel) allows users to discover all public posts on that topic, making the hashtag symbol an essential tool for content discovery and viral marketing.
【Historical and Other Uses】 Before its social media fame, the hashtag symbol had several important traditional uses: in the United States, the hashtag symbol has long been used as the "pound sign" on telephone keypads and in weight measurements (e.g., 10# means 10 pounds); in music, the hashtag symbol is similar to the sharp symbol ♯ (though they are distinct characters); in programming, the hashtag symbol is used as a comment marker in languages like Python and Perl, and as an ID selector in CSS. The hashtag symbol # truly bridges the analog and digital worlds.
How to Type hashtag symbol
Windows Input
Method 1: Press Shift + 3 on most US/UK keyboards; Method 2: Hold Alt and type 35 on the numeric keypad; Method 3: Type jinghao (pinyin for hashtag/number sign) or hashtag in the Microsoft Pinyin input method and look for # in the candidate list.
Mac Input
Method 1: Press Shift + 3 on most US keyboards; Method 2: On UK keyboards, press Option + 3 to type the hashtag symbol #; Method 3: Press Control + Command + Space to open the Character Viewer and search for "number sign".
HTML/CSS Input
HTML: # or #; CSS: content: "\0023";
LaTeX Input
Use \# to type the hashtag symbol # in LaTeX (the backslash escapes it from being interpreted as a macro character). In text mode, it's safer to use \# directly; in some contexts, you may also use the \text{\#} or the textcomp package for consistent rendering of the hashtag symbol.
hashtag symbol FAQ
What is the difference between the hashtag symbol # and the sharp symbol ♯?
The hashtag symbol # (U+0023) is a character with intersecting horizontal and vertical lines, used for number signs, pounds, and social media hashtags. The sharp symbol ♯ (U+266F) is a musical notation character consisting of two vertical lines and two diagonal strokes, used to indicate that a note is raised by a semitone. They look similar but are different characters with entirely different purposes: the hashtag symbol is for digital and general use, while the sharp symbol is exclusively for music notation.
Why is the hashtag symbol # called 'octothorpe'?
The hashtag symbol # is officially called the "octothorpe" by some standards organizations. The term is believed to have been coined at Bell Labs in the 1960s when designing the telephone keypad. The "octo-" refers to the eight points of the symbol (the four endpoints of the lines), and "-thorpe" may have been inspired by the surname of Olympic athlete Jim Thorpe or a combination of the Middle English word for "village" (thorpe) and the eight points. Despite its official name, the hashtag symbol is rarely called octothorpe in everyday conversation.
How do I create a hashtag with the hashtag symbol # on social media?
To create a hashtag using the hashtag symbol # on social media, simply type the hashtag symbol # immediately followed by a word or phrase without spaces. For example: #MondayMotivation, #travel, #ArtificialIntelligence. For phrases with multiple words, use capital letters for each word (CamelCase) for readability (e.g., #ThrowbackThursday) or combine words with underscores if preferred. Clicking on the hashtag symbol # followed by the topic will show you all public posts containing that hashtag.
What is the Unicode codepoint for the hashtag symbol #?
The Unicode codepoint for the hashtag symbol # is U+0023. Its decimal HTML entity is # and its hexadecimal entity is #. The named HTML entity is not commonly used, as the hashtag symbol is directly available in all character sets. The hashtag symbol resides in the basic ASCII block and is one of the earliest and most universally supported characters in all digital systems and fonts.
How is the hashtag symbol # used in programming languages?
The hashtag symbol # has various uses in programming: in Python and Perl, it marks the start of a comment (everything after # is ignored by the interpreter); in CSS, it serves as an ID selector (e.g., #header selects the element with id="header"); in C/C++ preprocessor directives, #include and #define use the hashtag symbol; in Ruby, the hashtag symbol is used for instance variables; in URL fragments, it indicates a specific section of a page (e.g., page.html#section1). The hashtag symbol is thus one of the most versatile characters in programming syntax.