A marathon or watchalong is an event in which viewers or readers engage many hours' worth of media (film, television, books, YouTube videos etc.) in a condensed time period. This phrase represents a two-fold shift from binge-watch in that it incorporates other media (not just television) and it reduces the negative connotations associated with bingeing. In the 2014 book Media Marathoning: Immersions in Morality, Lisa Perks describes media marathoning as a "comprehensive and complimentary phrase" that "connotes a conjoined triumph of commitment and stamina. This phrase also captures viewers' or readers' engrossment, effort, and sense of accomplishment surrounding their media interaction." Netflix executive Todd Yellin is quoted as saying "I don't like the term 'binge,' because it sounds almost pathological. 'Marathon' sounds more celebratory."

Media marathons can be organized around particular series, particular artists (e.g., Kurosawa or Hitchcock), or genres (e.g., horror films or chick flicks). Marathons can be user-created: one person decides to undertake a marathon solo or to organize a group marathon. Marathons may also be producer-created. Producer-created marathons are usually orchestrated by movie theaters, fan sites, or by cable channels that show already-run seasons, and, more recently, with original first-run programming through streaming services (such as Netflix's House of Cards). In television, a marathon is an extension of the concept of block programming.

The most common reasons for a network to run a marathon are:

Marathons are attractive to genre movie fans, or families that like watching their favorite movies/TV shows in blocks at a time.

Starting in the late 1940s, Journalists began using "marathon" in association with television events, according to archival research by media scholar Emil Steiner. "TV marathon" usages from 1949 to 1959 adhered to these categories: (1) Telethon, (2) Political Stunt/Punditry, (3) Lengthy Oratory, (4) Plus-Sized Show, (5) Plus-Sized Series, and (6) Plus-Sized Programming. “TV marathon” remained associated with live fundraising events through the early 1950s. This remained the most frequent journalistic usage of “marathon” until the 1980s, though the frequency really began falling in 1952, as journalists and style guides began using telethon instead. The portmanteau saved typesetters between two and 10 letters per mention of the most common usage of “television/TV marathon.” The While “movie marathon” appeared as early as 1948, journalists did not describe viewing them as “TV marathons.” Even when televised movie marathons began becoming common in the 1970s, journalists modified marathons by the content's original medium. Films and TV shows were separated, and journalists stuck to these six usages. “TV marathon” was used nearly 10 times more frequently than “TV binge” in English language periodicals from 1948 to 2011.

Japanese manga magazine Weekly Shōnen Jump developed a successful formula of publishing individual manga chapters and then compiling them into separate standalone tankōbon volumes that could be "binged" all at once. This Jump formula produced major Japanese pop culture hits such as Dragon Ball (1984 debut), One Piece (1997 debut) and Naruto (1999 debut). According to Matt Alt of The New Yorker, "Jump presaged the way the world consumes streaming entertainment today."

Marathon viewing sessions of Japanese anime television series have been a common trend in anime fandom for decades, dating back to the late 1970s to 1980s. According to an early American anime cosplayer, Karen Schnaubelt, Japanese anime were "incredibly difficult to come by" with "nothing available except broadcast TV until" VHS videotapes became commonly available in the late 1970s, allowing fans to import anime shows from Japan; she noted that a friend "would record the episodes" and then "a group of us would gather at his apartment and watch a marathon of the episodes." At comic conventions and sci-fi conventions in the 1980s, fans brought video tapes to hold marathon anime screenings; BayCon 1986, for example, held an 80-hour long anime marathon.

On broadcast TV, the first TV marathons aired on Nickelodeon's Nick at Nite, on July 1, 1985, presenting multiple episodes from Donna Reed and Route 66. The idea by Alan Goodman and Fred Seibert was based on a similar concept that radio stations used, in which songs by one particular artist would be played for a prolonged period of time.