When you enter the local BDSM community one of the events you may be exposed to is a play party. A play party is an essentially a party where BDSM play can occur. Groups hold parties as a way to learn and educate on safe play methods, chat about topics and generally hang around.
Parties usually have you sign a consent form saying you are aware of what's going on, waive any obligation of the homeowner for any injury and confirming you are old enough to be there (18 or 21 depending on the group). Smaller parties usually bring snacks to share. Alcohol may or may not be allowed. I know that most will not allow you to play if you are drinking.
There are two types of parties. Public parties and private parties. These can be very different from each other. Public parties are generally open to all group members. I've never seen alcohol allowed at these parties. Edgier and messier play is usually not allowed. Sexual play can be not allowed. All public parties I've been too have restricted play and not allowed any penetration at all. Private parties are a different beast. Since they are held in private homes and run by the homeowner and not the group they can set their own rules. Sex may be allowed, alcohol may be allowed. Different edgier play may be allowed. It's all up to the person hosting the party.
Learning about play parties may be intimidating at first but they don't have to be. If you wonder, you can ask what the rules of the party are before attending. It may help you relax a bit when it comes to your first one. Attending a play party does not obligate you to play. Many of the parties I've been to have included people there just to watch, BDSM chat and enjoy the other party aspects of food, drink, and conversation. You do not have to dress in fetish attire at a party.
Now that you know what a play party is, do you have any specific questions you'd like me to cover?