Most of the air purifiers use a conventional technology for filtration and purification of air – HEPA or High Efficiency Particulate Arresting filters. These filters arrest and segregate the unwanted particles from the air we breathe. However, the Filterless Air Purifier follows a totally different technology. These are mostly electronic and operate through the principle of ionization. There are to oppositely charged plates that arrest the unwanted particles and keep them from circulating in the air. See product reviews online.