The book introduces poroid aphyllophoroid fungi (bracket fungi or polypores) found in Finland and in neighbouring areas. In all, 273 species are dealt with, of them 251 known to occur in the country. The introduction discusses the systematic position of these fungi, their different distribution patterns, ways of life and pathology (especially wood decay), ecological aspects (including predecessor-successor relationships), and reasons for some species being threatened. A revised standard method is presented for assessing and comparing the conservation values of different forest areas, based on selected wood-inhabiting fungi. Structures and terms of macroscopy and microscopy are explained and illustrated. Each species is fully described, supplemented with hints for identification, a list of host trees and other ecology, outlines of distribution, and Red List status (NT and higher ranks); drawings of spores and other details were prepared for the species. An updated generic division was adopted with the help of colleagues working with DNA phylogeny. Each genus having two or more species in the area was provided with a key to the species. A key to pileate and effused-reflexed species was compiled on the basis of macroscopical characters, and an all-inclusive key was prepared based on both macroscopy and microscopy. Spore dimensions in the descriptions are based on measurements of several specimens per species, 30 spores measured from each of them, showing typical range (90%), and extreme values given in parentheses. Almost all the species are illustrated with one or more colour photographs (in all over 460 of them) taken in the field.