An asterisk is a typographical symbol that looks like a star and is usually five- or six-pointed in print and six- or eight-pointed when handwritten. It is called an asterisk because it resembles a conventional image of a heraldic star. The most common use of an asterisk is to call out a footnote, which is a note at the bottom of a page that provides additional information about a particular word or phrase in the text. It is also often used to censor offensive words. In computer science, the asterisk is commonly used as a wildcard character, or to denote pointers, repetition, or multiplication. In mathematics, the asterisk is used to designate a correspondence between two quantities denoted by the same letter – one with the asterisk and one without. Other uses of an asterisk include:

• Denoting zero or more repetitions of a pattern in regular expressions, which is also known as the Kleene star or Kleene closure.
• Denoting zero to many classes in the Unified Modeling Language.
• Censoring over all or part of a word.
• Indicating items of a list as an alternative to typographical bullets.
• Arranging a group of three asterisks in a triangular formation, which is called an asterism and may be used instead of a name on a title page.

In summary, an asterisk is a star-shaped symbol that has various uses in writing, including calling out footnotes, censoring offensive words, and denoting repetitions or multiplication in computer science and mathematics.