Number sign

Number sign
In Unicode	U+0023

The number sign (/ˈnʌmbər saɪn/ ), also known as the hash, pound sign, or octothorpe, is a typographical symbol with the appearance of two horizontal lines intersecting two vertical lines. It is represented by the symbol "#" and is used in various contexts across different fields.

History

The number sign has a rich history, with its origins tracing back to the 14th century. It was initially used as an abbreviation for the Latin term "libra pondo," meaning "pound weight." Over time, the symbol evolved and was adopted in various languages and contexts.

Usage

Mathematics

In mathematics, the number sign is occasionally used to denote a number, especially in informal contexts. For example, "#5" can be read as "number five."

Computing

In computing, the number sign is widely used as a comment symbol in many programming languages, such as Python and Perl. It is also used in URLs and as a delimiter in various data formats.

Social Media

The number sign gained significant popularity with the advent of social media, where it is used as a "hashtag." A hashtag is a word or phrase preceded by the number sign, used to categorize content and facilitate searches. For example, "#healthcare" might be used to tag posts related to healthcare topics.

Telecommunications

In telecommunications, the number sign is used on telephone keypads and is often referred to as the "pound key." It is used in various dialing sequences and as a control character in voicemail systems.

Music

In music, the number sign is sometimes used to denote a sharp note, although the official symbol for a sharp is different (♯).

Cultural Variations

The number sign is known by different names in various English-speaking countries. In the United States, it is commonly referred to as the "pound sign," while in the United Kingdom and other Commonwealth countries, it is often called the "hash."

Also see

• Hashtag
• Pound sign
• Sharp (music)
• Telephone keypad
• Comment (computer programming)