This publication summarizes knowledge accumulated in fuel research since the beginning of the 1960s. It concentrates on the "advanced fuels" for the current different types of reactors, including metallic, carbide and nitride fuels for fast reactors, so-called “cold” fuels and fuels to burn excess ex-weapons plutonium in thermal power reactors. Emphasis is given to aspects of fabrication and irradiation behaviour of these fuels. Basic data on essential properties that help to understand the phenomena are also included.