Dabbing in the cannabis world is when you smoke cannabis concentrates by heating an element commonly referred to as a "nail" and dabbing a glob of concentrates onto the hot nail and then inhaling the smoke through a rig designed for such purposes. It's most common in areas where cannabis has been legalized for one reason or another because it's simply easier to get in those places. Creating those cannabis concentrates using flammable solvents, most often butane, is what you normally read about when people blow their houses up being stupid with those flammables. I highly recommend staying away from that whole business. I've heard it can wreck your tolerance and cause you to no longer be able to even get high off normal cannabis flowers anymore if you do it too often. Kinda like the coke addicts moving on to smoking coke (free basing), or crack because the powdered coke no longer gets the job done for them, and pain pill addicts moving on to heroin because it's cheaper and stronger. Cannabis concentrates are stronger by a long shot simply because it's a lot more concentrated THC, but it's more expensive because of all the solvents and vacuum ovens required. Pushers gotta pay for the equipment, ya know? Personally I don't know any "dabbers", but I suspect they're willing to pay the higher price because they no longer get good and stoned off plain old cannabis flowers anymore. And personally, I don't understand anyone wanting to do that to themselves. Look it up on youtube some day and watch those crazy nuts cough up a lung for 15 minutes after taking a "dab".
Then again, you might enjoy watching them cough up a lung and drool and puke all over the place. It is entertaining.