Weed vaporizers achieve their purpose as a result of heating up herbs to the required temperature so the chemicals active in the weed boil off into a vapor which can be inhaled. This is a great deal safer in comparison with smoking or injesting the herb since it provides a much larger degree of control over dosage and there are considerably less unintended side effects.
Weed vaporizers use different techniques of heating the herb like thermal conduction, thermal radiation and convection. Thermal conduction is by far the most typical technique where the ingredient is placed onto a surface which is heated up by butane or a similar heat source which in turn heats up the herb that causes it to release its chemicals in vaporous form. Radiation uses an intense light source to send energy into the weed and is not as commonly used. Convection vaporizers heat the air in the vaporizers and having the air heat the herb.
Since different substances have different natural vaporization temperatures it is vital for a weed vaporizer to be able to control the temperature. To provide an example, weed has a vaporization temperature of 177°C while tobacco has a vaporization temperature of 140°C. Being able to accurately set the correct temperature will mean that you get the most chemicals out of your herbs.
Some weed vaporizers provide electronic displays that show both the actual and preset temperatures so that you can set it precisely as you would like it. It happens to be a question of personal preference however for weed it has to be more than 140°C which is the temperature at which trace amounts of THC can be found but below 200°C because toxins start forming at this high temperature. Many vaporizer users normally choose temperatures about 185°C since this is well under the toxin limit but high enough so that suitable amounts of THC and vapor make their way into the collection/inhalation device.
One particular point to be aware of is the density of the vapor will not make any difference to the effect which inhaling the vapor has on you. Less dense vapor that you would get with lower temperatures can easily contain as much THC as the thicker vapor you get by using increased temperatures.