You may have seen the term 'dripping' used on countless sites devoted to vaping and e-cigs. Well, it is still vaping regular e-juice, but instead of filling up a tank, you instead 'drip' a few drops of e-liquid directly onto the coil or bridge of an atomizer, and then puff away.
Dripping tends to produce denser vapor clouds with cleaner, bolder flavors. Dripping is also nice if you want to vape a variety of different flavors in one sitting without having to switch off tanks. Obviously there are times when using a cartomizer is better, like while driving.