HEPA stands for high-efficiency particulate absorption. HEPA is a type of vacuum filtration system that traps a large amount of very small particles that other vacuum cleaners might recirculate back into the air. There are two types of HEPA filters that you can find in vacuums cleaners: true HEPA and HEPA-like filters. True or absolute HEPA vacuum filters trap at least 99.97 percent of particles, while HEPA-like filters only trap 85 to 90 percent of particles. Vacuum filters must pass a test set by the United States Department of Energy to truly be considered HEPA, but the results are cleaner air and less dust while you vacuum.