Serial primarily refers to the presentation of works in sequential segments, a format found across literature, publishing, and radio/television, including the short-subject theatrical film series popular during the 1930s and 1940s. In the modern media landscape, it is famously recognized as Serial, a groundbreaking podcast launched in 2014 as a spinoff of This American Life that investigates a single true-crime story over multiple episodes. In computing and technology, the term describes the process of serial communication, which transmits data one bit at a time, and is central to numerous hardware standards such as USB, Serial ATA, and the Serial Peripheral Interface Bus (SPI). Beyond these fields, "serial" also denotes a serial number (an identifying code), the grammar usage of a serial comma, and a serial killer—a person who commits multiple murders. Additionally, the term has a specific mathematical definition referring to a binary relation in which every element of a set is related to some other element. Finally, the word is a common homophone for "cereal," and it is distinct from the musical and philosophical concept of serialism.