What about it? BDSM encompasses everything from fuzzy hot pink handcuffs all the way over to using another human as a toilet. Pretty much it's an all-encompassing term for people with sexual kinks.
Not much of a discussion or starter really.
BDSM as a subject is really kind of a misnomer as it breaks down into so many damn sub categories, and then depending who you're talking to the same term has different meanings or connotations.
It's a rather complex subject with a 4 letter acronym that basically means "Taboo" to most.
If I say, "I'm into BDSM" you're going to think I'm some leather chap wearing freak that walks on my hands and knees with a collar and leash on all day that lives in a kennel and eats out of a dog bowl while being whipped and having a woman step on my bits wearing spiked heels.
Which, while an amusing picture is really really far from the truth.
Tying your lover up with silk scarves falls under BDSM. It's the very light side of it, but it's part of it. Or using rope (Shibari) , or chains, or cuff restraints, or suspension gear, or whips, or floggers, or paddles, or collars, or cuffs, or play piercings, or urethral sounds, magic wands (electro stim), feathers, role-playing, or edge (knife/cutting) play, or wax, or chastity belts, or household chores, or spanking, or hair pulling, or fire play, or bondage tape, or or or... Seriously, it's a pretty lame term to throw out for a topic.
Or, perhaps you've decided that you're going to dominate your lover in bed and bend them to your will that evening.
It would probably be better if you broke it down into areas of interest for discussion instead.
IE: Spanking
Then restraints
Maybe d/s (I refuse to do that ****ing dominant/submission stutter crap that ends up with people typing shit like W/we to mean me and my sub...)
Or even pain play.
Then maybe do some talk on Role-playing
I can pretty much intelligently cover most topics surrounding the general topic of BDSM without resorting to Wikipedia (No offense) to discuss it.
Including how to do it safely. Which is one of the absolute most important things.
"Well, then," the Cat went on, "you see a dog growls when it's angry, and wags its tail when it's pleased. Now I growl when I'm pleased, and wag my tail when I'm angry. Therefore I'm mad."