Definition of pound sign

The pound sign (#) is also known as the hash sign, number sign, or octothorpe. Its origin can be traced back to the world of telegraphy in the late 19th century. The term "octothorpe" derives from the shape of the sign when written on graph paper, resembling eight wedges or angles. In telegraphy, the pound sign was used as a signaling character, representing the sound of a double bell. Since telegraph lines could only transmit Morse code, which consists of dots and dashes, the pound sign was necessary to differentiate between tones. In the era of typewriters, which lacked the numerical key for the zero, the pound sign was repurposed to indicate the digit "0." This usage emerged in the early 20th century and remains common today, especially in certain numerical conventions, such as telephone numbers and postal codes. The pound sign's significance in computing dates back to the 1960s, when it was used in programming languages like COBOL and SQL as a wildcard character, matching any sequence of characters. In recent years, it has gained newfound popularity due to its use as a hashtag symbol on social media platforms like Twitter and Instagram, creating a new linguistic phenomenon known as "hashtag culture." Today, the pound sign serves multiple functions in various contexts, reminding us of its varied and multilayered history.