A category meant to represent an individual’s most likely means of HIV transmission. An individual getting tested is assigned to an exposure category based on reported HIV risk factors collected on the test requisition form. Exposure categories are mutually exclusive, which means an individual can only be assigned to one category. When more than one exposure category is applicable for a single individual, a hierarchy is used to assign them to a single category. This hierarchy is based on the level of HIV risk associated with different exposure categories. While data on HIV testing are broken down by exposure categories, data on new HIV diagnoses (i.e. HIV-positive tests) are broken down by non-mutually exclusive priority populations. See technical notes for more information on exposure categories.