What Is a Pound Key? Unlocking Its Meaning

Pound Key

Have you ever wondered what that computer keyboard pound key symbol, also known as the hash sign, really means? You know, the one that looks like a tic-tac-toe board or a #? The pound sign, also known as the hashtag, resembles a typewriter’s abbreviation for the word “number”. Well, let me shed some light on the abbreviation for you. Given the text, I have the answers to your phone questions.

The pound key, also known as the hashtag symbol or abbreviation, is more than just a quirky character found on telephone keypads and computer keyboards. The phone has become an integral part of our digital lives, especially on social media platforms. It has revolutionized the way we communicate and connect with others. From sharing photos and videos to staying updated with the latest news, the phone has become a powerful tool in our hands. With just a pound sign, we can now reach a wider audience and join conversations on various topics. So, it’s no wonder that the phone has become a necessity in today’s fast-paced world. You’ve probably seen the pound sign used to categorize or group content under specific topics or themes.

But did you know that the pound key has various other meanings too? In different contexts, it represents the number sign (#), denoting numerical values or serving as a shortcut in programming languages. So whether you’re scrolling through your favorite social media feed or tinkering with coding projects, keep an eye out for this versatile pound sign symbol.

Pound Key

Pound key vs. number sign

The pound key (#) and the number sign ($) are distinct symbols. While they may appear similar at first glance, they have different meanings and uses in various contexts.

The pound key is used in phone numbers

One way to differentiate between the pound key and the number sign is by their usage in phone numbers. The pound key, also known as the hash sign or simply the pound sign, is commonly found on telephone keypads. In this context, it serves as a special character that allows users to navigate through automated phone systems or access certain features. For example, when prompted to enter an extension or code, you may be instructed to press the pound key followed by a specific number.

The number sign represents currency

On the other hand, the number sign is primarily associated with currency symbols. It is commonly used to denote monetary values in different countries around the world. For instance, when referring to prices or financial figures, you might come across phrases like “US$10” or “€50,” where the dollar ($) and euro (€) signs are preceded by the number sign.

The pound key is commonly associated with hashtags

In recent years, due to its resemblance to a tic-tac-toe grid, the pound key has become synonymous with hashtags on social media platforms such as Twitter and Instagram. Hashtags are used to categorize content and make it more discoverable by others interested in similar topics. By including a hashtag before a keyword or phrase (e.g., #travel), users can easily search for related posts and join conversations within specific communities.

The number sign denotes numerical values

While the pound key has found its place in digital culture through hashtags, the number sign continues to serve its traditional purpose of representing numerical values. In mathematical equations or coding languages like JavaScript or Python, you will often encounter instances where variables are denoted using this symbol. In music notation, the number sign is used to indicate a sharp note.

Historical origins of the pound key

The pound key, also known as the hashtag symbol (#), has an interesting historical background that dates back several centuries. Its origins can be traced to the abbreviation “lb” for libra pondo, which is Latin for “pound weight.” Let’s delve into the fascinating journey of how this symbol came to be and its significance in various contexts.

The first appearance of the pound key can be attributed to typewriters in the late 19th century. Typewriters were widely used for written communication before computers became commonplace. The inclusion of the pound key on typewriters allowed individuals to easily indicate a unit of weight or quantity with just a single character. This made it convenient for business correspondence and other documents that required such measurements.

However, it was not until 1968 that the pound key gained prominence in telecommunication when Bell Labs adopted it for use on touch-tone telephones. The touch-tone system revolutionized telephone communication by replacing rotary dials with buttons, enabling faster and more efficient dialing. The inclusion of the pound key on these new phones provided users with additional functionality beyond just dialing numbers.

Fast forward to 2007, and we see another significant milestone in the history of the pound key – its popularization through its association with hashtags on Twitter. Hashtags were initially introduced on Twitter as a way to categorize tweets and make them easier to find within specific topics or conversations. Users began incorporating hashtags into their tweets by simply prefixing keywords or phrases with the pound symbol (#). This practice quickly caught on, leading to widespread adoption and making hashtags an integral part of social media culture.

The rise of hashtags brought about a new way of organizing online content and facilitating discussions around specific subjects. It allowed users to discover related posts from others who shared similar interests or participated in ongoing conversations. Hashtags became so prevalent that they extended beyond Twitter and are now commonly used across various social media platforms, including Instagram, Facebook, and LinkedIn.

Different names for the pound key

The pound key, also known as the hashtag symbol (#), goes by various names depending on regional variations and specific contexts. Let’s explore some of these different names and how they are used.

Octothorpe, hash, or square

One of the most common names for the pound key is “octothorpe.” The origin of this term is a subject of debate, but it is believed to have been coined by engineers at Bell Laboratories in the 1960s. The word combines “octo,” referring to the eight points on the symbol, with “thorpe,” a reference to Jim Thorpe, an Olympic athlete known for his versatility in multiple sports.

In addition to octothorpe, people refer to the pound key as “hash” or “square” in various parts of the world. These terms are often used interchangeably and have become widely recognized due to their association with social media platforms like Twitter and Instagram. For instance, when posting on these platforms, users include hashtags (a term derived from hash) to categorize their content and make it easily discoverable.

Tic-tac-toe symbol or grid mark

Another way people refer to the pound key is by associating it with a game many of us played during childhood: tic-tac-toe. The symbol’s grid-like appearance resembles that of a tic-tac-toe board, which led to its colloquial name as the “tic-tac-toe symbol.” This playful moniker highlights its resemblance and adds a touch of familiarity when discussing this particular character.

Sharp symbol in music notation and crosshatch symbol in cartography

Outside of digital communication and gaming references, there are other domains where alternative terms are used for the pound key. In music notation, especially for piano players and composers, it is referred to as the “sharp symbol.” The sharp symbol indicates that a note should be played one semitone higher than the natural note.

In cartography, the pound key takes on yet another name: the “crosshatch symbol.” This term is used to describe the pattern created by intersecting horizontal and vertical lines, resembling a grid. Cartographers use this symbol to represent areas with dense vegetation or other features on maps.

Pound key in computer programming

The pound key, also known as the hashtag or octothorpe symbol (#), serves various purposes in computer programming. This versatile symbol is used to define preprocessor directives in programming languages like C and C++. It plays a role as an anchor link identifier within HTML documents and serves as a delimiter for macro expansion and stringification operations.

In the realm of computer programming, the pound key is not just another character on a computer keyboard; it holds significant importance for programmers worldwide. Let’s explore its various applications:

Preprocessor Directives

In languages such as C and C++, the pound key is used to define preprocessor directives. These directives guide the compiler during the compilation process by performing actions before the actual code execution begins. They are typically placed at the beginning of a source file and begin with a pound sign followed by specific keywords.

For example:

#include <stdio.h>
#define PI 3.14159

Here, the #include directive tells the compiler to include the standard input/output library, while #define creates a constant named “PI” with a value of 3.14159.

Anchor Link Identifier

Within HTML documents, the pound key serves as an anchor link identifier. An anchor link allows users to navigate through different sections of a webpage quickly. By assigning an id attribute to an element within HTML code and using that same identifier preceded by a pound sign in a URL, users can jump directly to that specific section.

For example:

<a href="#section2">Jump to Section 2</a>


<h2 id="section2">Section 2</h2>

In this case, clicking on “Jump to Section 2” will take users directly to <h2 id="section2">Section 2</h2>.

Delimiter for Macro Expansion and Stringification

The pound key also serves as a delimiter in macro expansion and stringification operations. In C and C++, macros are used to define reusable code snippets. The pound sign is used in combination with other preprocessor directives to manipulate the code at compile time.

For example:

#define STRINGIFY(x) #x


printf("%s", STRINGIFY(Hello World!));

In this case, the STRINGIFY macro converts the argument into a string literal by placing it within quotes. The resulting output will be “Hello World!”.

Pound key in mathematical notation

The pound key, also known as the hashtag symbol (#), has various uses in mathematical notation. Let’s explore its different roles and how it is employed within the field of mathematics.

Cardinality of Sets

One of the primary applications of the pound key in mathematical notation is to indicate the cardinality of sets. When placed before a set name, such as #A, it signifies the number of elements present in that particular set. For example, if we have a set A containing five elements, we can represent its cardinality using #A = 5.

This usage allows mathematicians to easily express and compare the sizes of different sets without explicitly listing their elements. It provides a concise way to convey important information about sets and aids in various mathematical operations involving set theory.

Logical Negation

In addition to representing cardinality, the pound key serves as a symbol for logical negation when placed before a statement. For instance, if we have a statement P that asserts “it is raining,” then #P would denote “it is not raining.” This negation operator helps mathematicians express contradictory or opposite statements within logical frameworks.

By utilizing this notation, mathematicians can manipulate logical statements and construct complex arguments while maintaining clarity and precision. The pound key’s role as a symbol for logical negation plays an essential part in formal logic systems used across numerous branches of mathematics.

Symbolizing Parallel Lines

Within geometric proofs and discussions on Euclidean geometry, the pound key takes on yet another meaning. It represents parallel lines when used within geometric contexts. By placing two pound symbols (##) between two lines or line segments, mathematicians indicate that those lines are parallel.

This symbolism aids in visually demonstrating relationships between geometric figures and helps establish important properties within geometrical proofs. The use of the pound key to represent parallel lines simplifies communication among mathematicians studying geometry and facilitates clearer explanations.

Pound key in social media hashtags

The pound key, also known as the hash symbol (#), plays a significant role in social media hashtags. It enables users to tag their posts with relevant keywords or topics, allowing for easy content discovery and categorization on platforms like Instagram.

Hashtags have become an integral part of social media culture, revolutionizing the way we search for and engage with content. By using the pound key followed by a keyword or phrase, users can join conversations and connect with others who share similar interests. Let’s explore how this simple symbol enhances engagement and reach on various social media platforms.

Facilitates content discovery and categorization on platforms like Instagram

On platforms like Instagram, where millions of photos are shared every day, hashtags serve as a powerful tool for organizing and finding specific content. When users include relevant hashtags in their captions or comments, it becomes easier for others to discover their posts through targeted searches.

For example, if someone is interested in cooking recipes, they might search for #foodrecipes or #cookingtips. By including these hashtags in their posts, creators ensure that their content appears in front of people actively seeking such information. This not only increases visibility but also helps build a community around shared interests.

Enhances engagement and reach by connecting users with similar interests

One of the primary benefits of using hashtags is the ability to connect individuals who share common passions or hobbies. When users click on a hashtag within a post or search for it directly, they are presented with a feed of all public posts that include that particular hashtag.

This feature allows users to interact with like-minded individuals beyond their immediate network of followers. They can engage in discussions, exchange ideas, and discover new accounts to follow based on shared interests. Hashtags act as virtual meeting points where people from different backgrounds can come together around a common theme.

The evolution from “pound” to “hashtag”

Interestingly, the pound key’s association with hashtags stems from its historical use on telephone keypads. Before the advent of social media, the pound key was primarily known as a symbol used in touch-tone dialing systems.

In the early days of Twitter, users repurposed the pound key to categorize their tweets and make them more discoverable. This practice quickly caught on, leading to the widespread adoption of hashtags across various social media platforms. Today, the term “pound” is rarely used when referring to hashtags, with “hashtag” or simply “tag” being the preferred terminology.

Other names for the pound key

While most people are familiar with calling it a hashtag or hash symbol, there are other names associated with this versatile character.

Pound key in currency symbols

The pound key, often referred to as the hashtag symbol (#), is a widely recognized character that has become an integral part of our digital communication. However, it is important to note that the pound key is not directly associated with currency symbols like the British pound (£) or the US dollar ($). In fact, its primary usage lies outside the realm of monetary value.

Currency Symbol Pound Key
LBP ل.ل
SYP ل.س
SDG ج.س

Not directly associated with currency symbols

Contrary to popular belief, the pound key does not represent any specific currency. It is primarily used in social media platforms and online conversations to categorize or group posts under a specific topic or theme. When used in this context, it is known as a hashtag. For instance, if you come across a post on social media with “#travel,” clicking on this hashtag will lead you to other posts related to travel. This feature allows users to easily discover content and engage in discussions centered around particular subjects.

Represents weight measurement

While the pound key may have gained prominence through its association with hashtags, its origin lies in representing weight measurement in pounds. In various industries such as logistics, manufacturing, and agriculture, the pound symbol (#) denotes pounds when used alongside numeric values. For example:

  • 10# refers to 10 pounds

  • 5# can be interpreted as 5 pounds

This usage ensures clarity when discussing weights and measurements within these sectors.

Distinct from currency symbols

It is crucial to differentiate between the pound key (#) and currency symbols denoting specific currencies worldwide. Currency symbols such as £ for British pounds or $ for US dollars serve as abbreviations or visual representations of their respective currencies. They are utilized extensively in financial transactions and international trade.

On the other hand, the pound key serves different purposes altogether – from organizing online content through hashtags to indicating weights in certain industries. While both types of symbols involve characters displayed on keyboards or screens, they do not share the same meaning or usage.

Pound key in legal documents

The pound key, also known as the section symbol (§), plays a crucial role in legal documents. It serves as a reference tool for lawyers and researchers, aiding them in navigating complex legal texts efficiently. Let’s delve into the details related to its usage in legal documents.

Legal Document Type Use of Pound Key
Contracts Indicates monetary amounts or fees
Court Documents Denotes case numbers or docket numbers
Legislation Represents sections or subsections
Legal Citations Indicates volume and page numbers
Legal Briefs Marks important sections or arguments
Legal Forms Denotes required fields or placeholders
Legal Opinions Represents dissenting or concurring opinions
Legal Agreements Indicates terms or conditions
Legal Notices Marks important information or disclaimers
Legal Correspondence Represents reference numbers or file numbers

Used as a section symbol (§) to reference specific sections of a legal text

In legal documents, the pound key is commonly employed as a section symbol (§) to refer to specific sections within the document. This allows readers to easily locate and cross-reference relevant information without having to scan through lengthy texts. By using this symbol, lawyers can pinpoint precise sections that are pertinent to their case or research.

Indicates paragraph divisions within statutes or regulations

Another significant function of the pound key is indicating paragraph divisions within statutes or regulations. Legal texts often consist of numerous paragraphs that discuss different aspects of the law. By incorporating the pound key, these paragraphs are visually separated, making it easier for readers to identify distinct units of information. This aids comprehension and ensures that each paragraph receives appropriate attention.

Helps lawyers and researchers navigate complex legal documents efficiently

Legal documents can be intricate and dense with information, which makes navigation challenging for lawyers and researchers alike. The pound key simplifies this process by providing an organized layout that assists in locating specific sections or paragraphs swiftly. Its presence reduces time spent searching for relevant content, allowing professionals in the field to focus on analyzing and interpreting critical information effectively.

By using this simple yet effective symbol strategically placed throughout the document, lawyers can save valuable time during their research process while maintaining accuracy and precision.


Now that we’ve explored the pound key in various contexts, it’s clear that this symbol holds more significance than meets the eye. Whether you refer to it as a pound key or a number sign, its usage extends beyond just numerical purposes. From its historical origins to its presence in computer programming, mathematical notation, social media hashtags, currency symbols, and legal documents, the pound key has proven itself to be versatile and widely adopted.

So next time you come across the pound key on your keyboard or see it used in different settings, remember its multifaceted nature. Embrace its diverse applications and consider how it can enhance your own work or online presence. Whether you’re a programmer looking for shortcuts or a social media enthusiast trying to make an impact with hashtags, the pound key is here to assist you. Keep exploring all the ways this symbol can add value to your endeavors!

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By Kane Wilson

Kane Wilson, founder of this news website, is a seasoned news editor renowned for his analytical skills and meticulous approach to storytelling. His journey in journalism began as a local reporter, and he quickly climbed the ranks due to his talent for unearthing compelling stories. Kane completed his Master’s degree in Media Studies from Northwestern University and spent several years in broadcast journalism prior to co-founding this platform. His dedication to delivering unbiased news and ability to present complex issues in an easily digestible format make him an influential voice in the industry.

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