As the name suggests, pod systems are e-cigarettes that make use of a “pod” as opposed to a traditional tank or atomizer. They ultimately do the same job: they hold the e-liquid and vaporize it to deliver vapor to you through the mouthpiece.
They often have a smaller capacity than most tanks, at between 1 and 2 ml, although some pods are bigger. The pods simply push into place in the top of the device and pull out when you’ve emptied them or want to switch flavors.
In most cases, they have an automatic operation – so you just inhale from the tip to vape in the same way you would smoke a cigarette – but some have manual buttons like vape pens and mods.