Cov khoom uas pab tau cov pej xeem kom noj qab haus huv. Raws li WHO, cov khoom no yuav tsum muaj "txhua lub sijhawm, hauv cov tshuaj kom txaus, nrog rau cov ntaub ntawv zoo thiab cov ntaub ntawv txaus, thiab tus nqi uas tus neeg thiab zej zog them taus".