Vapourising is an alternative to smoking. It is achieved by heating cannabis slightly less than would cause it to burn but sufficiently hot to cause the THC and other oils to be released as vapour. The vapour is then inhaled and absorbed through the lungs in a similar fashion to smoking. It has many advantages over smoking in terms of efficiency and health and delivers a much faster hit than eating cannabis.
Vaporizers of various designs (and spellings!) have been around for many years now and are often found in Dutch coffeeshops and in places like the Cannabis College. They employ a variety of methods of heating the cannabis and delivering the vapour.
The simplest devices use a lighter to heat air in a glass tube which is then drawn over the bud by manual sucking.
More sophisticated designs use controllable electric heaters.
10 years ago I blagged a free Volcano from its makers. I still have it and still love it. I no longer have any affiliation with its makers but I still think it's the most stoner-proof, efficient and reliable vaporizer around. It pumps hot air through the marijuana, collecting the vapour in a roasting bag. Using a pump, rather than relying on inhaling, gives predictable airflow, enabling accurate temperature control.
The downside is that sucking vapour out of a bag looks a bit uncoolly like sniffing glue. It's also very un-portable and ridiculously expensive.