About SF ConventionsHistorians go to academic conferences, doctors attend medical seminars, lawyers have annual meetings of the Bar Association. So what's different about professional gatherings for science fiction writers? Well, there are the Klingons having lunch in the hotel coffee shop.
The truth is a little more complex. In fact, most SF conventions are organized and run by fans as volunteer operations. This doesn't mean that pro writers don't show up -- far from it, as many SF writers are fans themselves. It does, however, mean that the atmosphere is more casual than that of the typical business conference or trade show, and that you don't have to wait for evening to enjoy the entertainment portion of the program.
You can now find at least one SF convention ("con" for short) somewhere in North America on just about any weekend of the year, devoted to some aspect of SF fandom. Some cons emphasize specific subcategories -- costuming, filk music, televised SF, comic books, Japanese animation, literature, feminist SF, et cetera -- while others are more general in focus. Most are (or aspire to be) annual affairs, and the majority are held in the same city each year. A few, either the largest or the more specialized, move from place to place; among these is Worldcon, which has been held everywhere from Scotland to Australia. My "home convention" is OryCon, held each November here in Portland. I've been involved in various aspects of OryCon's production over the years -- at various times I've run its writers' workshop, coordinated its music programming, and/or overseen various con-related publications.
Klingons in the Hallways
What happens at an SF con? Almost anything, really. Dealers in books, DVDs, jewelry, and other SF-related merchandise display and sell their wares. Fans of particular books or TV shows may attend dressed as their favorite characters (thus the Klingons, as well as assorted aliens, wizards, barbarians, vampires, knights, and so on). Published writers discuss issues of craft, marketing strategy, and literary merit, autograph books for their readers, and accept dinner invitations from editors in hopes of landing lucrative book contracts.
Editors listen in on fannish conversations hoping to learn what readers are most interested in buying, then take writers to dinner in hopes they'll finish their novels more quickly. (Well-fed writers are said to write faster.) Novice writers attend panel discussions in hopes of finding the One True Secret to selling their short stories or novels. (There isn't one, but this hasn't stopped anyone yet.) Publishers throw lavish parties for writers and fans, hoping that a reputation for throwing lavish parties will translate into a reputation for publishing good SF.
Fans throw parties for each other, some more opulent than others, in hopes of attracting new fans to a particular TV show, series of books, or upcoming convention. There's often a formal costume competition, or masquerade, and there may be one or more concerts, a dance, or both, as well as informal filk circles. There may also be an exhibition of SF and fantasy artwork, frequently of high professional quality, with works available for sale or auction.
Exceptions & Advice
The above description applies, in some degree, to most fan-run cons. There's another breed of convention that does not follow this model -- the "professional" con, nearly always promoting a TV show such as Star Trek or Buffy the Vampire Slayer, put on for profit by a traveling production company. These are usually one-day affairs featuring very limited programming, a high-profile guest star from whatever TV series is being promoted, and the chance to buy expensive licensed souvenirs. While these can offer a decent opportunity to pick up current gossip about favorite TV shows and get a look at the actors, they're not particularly fan-friendly. (Note that not all media conventions are of this stripe. A rule of thumb: if the con is selling tickets, it's a professional con; if it offers memberships, it's probably a fan-run con.)
For considerably more detail about what happens at SF cons and how to survive one without sacrificing sanity or other valuable commodities, the materials contained in the Science Fiction Survival Kit for Newbies are an excellent reference.