BETA. The IAB Content Taxonomy V3 classifier categorizes text into 617 topics. It has a main category (e.g. sports, business or science) and a leaf category (soccer, agriculture or physics). The class name has 3 parts, separated by underscores: "main topic_sub topic_uid" where the uid is the category's official IAB unique id. This text classifier is based on the IAB Quality Assurance Guidelines (QAG) Content Taxonomy V3, released in September 2021.