Henry Jenkins writes: "Slash ... is simply one of a number of important forms of fan writing; one can survive quite comfortably within fandom without developing a taste for slash or without even reading any of it. Slash does, however, constitute a significant genre within fan publishing and may be fandom's most original contribution to the field of popular literature." (Jenkins 188)

But it's quite possibly a more basic question that you're asking: what is slash? The term was coined in the 1970s, after various short stories began to be written - and published in Star Trek fanzines - featuring Kirk and Spock exploring a homosexual relationship with each other. Kirk/Spock = Kirk-slash-Spock = "slash fiction". And our seminar title? One of the earliest available examples of K/S fiction is Gayle Feyrer's series, "The Cosmic Fuck", written in 1978 and 79.

These sorts of stories have long since expanded to include other fandoms, such as Blake's 7, The Professionals, Highlander, and The Sentinel. However, as it's Star Trek fans who coined the phrase and are generally attributed with popularizing (if in a small, insulated area) the genre, it's Star Trek we'll be looking at.