Slash fiction is fan fiction, describing gay pairings between media characters, often in explicit detail, and very frequently outside the canon of the source. The name arises from the use of the slash character in phrases such as 'Kirk/Spock' to describe the stories. ('Kirk/Spock' is widely thought to be the first type of slash fiction, first appearing in the 1970s in Star Trek fanzines.)
Slash fiction was among the earlier fan fiction known to have been written for Star Trek, with many show principals recalling letters sent in from mostly females. Slash writers were the first to call themselves 'trekkies', a reference to 'groupies' and stand as marked contrast to the modern more male-dominated trekker phenomenon. At least one officially licensed Trek novel was published containing slash elements: the 1985 novel Killing Time by Della van Hise . According to the Web site The Complete Starfleet Library, an early draft of the novel was erroneously published in which the author had included homosexual subtext between Kirk and Spock before an editor requested a revised version (which was subsequently published in place of the original version).
Today slash fiction is written, or at least explored, by a wide variety of people of all backgrounds and orientations. However, the majority of slash authors and slash fans are heterosexual women. Horror author Poppy Z. Brite's works, along with others, could be considered slash fiction by extension, although several of her characters are already gay and there is little need to further pair them off.
Although such descriptions (e.g. 'Kirk/Uhura') are also used to describe heterosexual relationship fiction, the term 'slash' usually implies a homosexual pairing (het being commonly used for similar heterosexual speculations). Indeed, the exact definition of the term has often been hotly debated within the various slash fandoms. The strictest definition holds that only stories about relationships between two male partners ('M/M') are 'slash'; this has led to the evolution of the term femslash to describe lesbian ('F/F') fiction. The recent appearance of openly gay characters on screen, notably Willow and Tara in the television series Buffy the Vampire Slayer and many of the characters in the Queer as Folk series, has added much to the discussion. Some hold that the term 'slash' only applies when the relationship being written about is not part of the source's canon, and that fan fiction about canonical same-sex relationships is hence not slash. However, abiding by this definition leaves such stories without a convenient label, so this distinction has not been widely adopted.
Some fan fiction aficionados might find erotic pairings of characters, regardless of gender, unpleasant for one reason or another, and so it is considered impolite to publish slash fiction without giving readers fair warning of explicit content within (sometimes including detailed warnings to the level of adult activity undertaken by the characters). However the prevailing attitude is that once a warning has been given anything goes, and readers who complain that they found a story with clear warnings offensive, that they continued to read, are generally derided.
Some groups differentiate between explicit slash stories and stories in which in which the same-sex pairing just happens to be friends and/or adult activity is 'off-screen' as being 'no lemon', whereas tales in which said activity on some level does occur (anything heavier than kissing) are labeled 'lemon'. 'Lime' is supposedly when nothing more explicit than kissing occurs. These terms ('lemon' and 'lime') most probably arose from the anime/yaoi fandoms.
It should also be noted that slash fiction can be of any rating: G, PG, PG13, R or NC17. Not all slash fiction has explicit sexual content: the interaction between two characters can be as innocent as holding hands or a chaste kiss. If a story contains themes which may offend or which some readers may find distasteful (e.g. non-consensual sex, incest, BDSM, or even simply heterosexual sex), it is considered polite to include warnings in the story header.
Occasionally some forms of erotic fiction can prove to be potentially controversial: in particular slash involving underage characters (often termed 'chanslash'; examples include some Harry Potter slash) or real people slash ('RPS': initially members of boy bands, and lately including actors (LOTR), musicians, sport figures and even prominent political figures) could be considered distasteful by those who otherwise find nothing objectionable about erotic fiction in general. An obvious viewpoint is that those who do not wish to read a certain story do not have to do so. It should be noted that in the case of stories involving real people the legal issues involved can be more complex than usual in fan fiction.
In recent years, slash fiction has become so prevalent on the Internet that an inaccurate stereotype has emerged among those unfamiliar with the genre that all fan fiction is slash (or at least romance) based, which has sparked concern among writers of non-slash fanfic.
While true that it could be a controversial subject, most slash fans find slash as natural and tasteful as het. They believe that when romance is not one of the overarching themes of the canon material, it is impossible to conclusively state that any character is straight, gay or bisexual. There is vociferous debate on the canonicity of any relationship (slash or het) on websites such as Fiction Alley.
In addition to fiction, slash artwork is widely available. In recent years, the advent of imaging software such as Adobe PhotoShop has allowed slash artists to manipulate photographs of their subjects to produce 'PG' or erotic images (a good example of this artwork can be viewed at The Theban Band), either as static pictures or animated GIFs.
Academic treatment of slash
Slash fiction was the subject of several notable academic studies in the early 1990s, as part of the cultural studies movement within the humanities. Notable studies included work by Constance Penley , originally written as an article and later expanded into her 1997 book Nasa/Trek, as well as Enterprising Women by Camile Bacon-Smith and Textual Poachers by Henry Jenkins. All of these books, as is characteristic of cultural studies, approach slash fiction from an ethnographic perspective, and talk primarily about the writers of slash fiction, and the communities that form around slash fiction. They focus only minimally on textual analysis. Following the heyday of cultural studies, academic work on slash has declined, but not disappeared; papers still pop up occasionally from within queer theory.