hashmark

Hashmark refers primarily to the typographic symbol '#' and to the various uses and names it has across languages and fields. In North America it is commonly called the pound sign or number sign on telephones and in print; elsewhere it is often called the hash or simply the hash mark. The symbol is also known by the term octothorpe, a name coined by Bell Labs in the 1960s.

In computing and writing, the hash symbol is employed in several ways. It is used to begin comments in many programming and scripting languages, to introduce directives in some contexts, and to denote headings in markup systems such as Markdown. In URLs, a hash introduces a fragment identifier that points to a specific section within a page or resource. The symbol therefore functions as punctuation, a control character, and a structural marker depending on the context.

Social media popularized hashtags, a usage in which a word or phrase follows the hash sign to create a topic label that can be searched and aggregated across posts. This modern convention has influenced data tagging and content discovery, though it is technically built on the same character used in traditional punctuation.

In sports, hash marks are the short lines on a field or rink that help mark yardage, alignment, and faceoffs. On American football fields, these marks indicate yard lines and help determine ball placement; in hockey, hash marks serve similar organizational purposes near the boards.

Regionally, the symbol has diverse names and uses. The United States often uses “pound sign” for the symbol on telephones, while the United Kingdom prefers “hash.” The term hashmark can therefore refer to the character itself as well as to field markings in sports.