Revised WHO 2016 classification of tumors of the central nervous system (CNS) incorporates for the first time genetic information in addition to morphology for classification of many tumor entities. One of the most important changes is restructuring the chapter of diffuse gliomas. Based on shared genetic driver mutations, diffusely infiltrating astrocytomas and oligodendrogliomas are now classified together, separately from "other" glial tumors with a more circumscribed growth pattern, different pathogenesis and clinical outcome. Diffuse gliomas can now be more objectively diagnosed and further prognostically stratified by use of a relatively small number of markers (ATRX and IDH1/2 mutations and del 1p/19q). Another newly genetically-defined and clinically relevant entity is diffuse midline glioma, H3 K27M-mutant. Some glioma entities, variants and growth patterns were deleted and new variants, such as epithelioid glioblastoma and glioblastoma with a primitive neural component were added. In the article, the most important changes of diffuse gliomas classification are summarized and a practical diagnostic approach is illustrated.