Nature Reviews Immunology provides in-depth coverage of all areas of immunology, from fundamental mechanisms to applied aspects. In addition to our review articles, we highlight recent developments and exciting new primary papers in the field, as well as reflecting on the people, papers and events that have influenced the development of immunology. Nature Reviews Immunology is part of the Nature Reviews portfolio of journals. Immunology is a diverse and growing discipline that can be defined as the study of the tissues, cells and molecules involved in host defence mechanisms. Immunologists attempt to understand how the immune system develops, how the body defends itself against disease, and what happens when it all goes wrong. Nature Reviews Immunology provides in-depth coverage of all areas of immunology, from fundamental mechanisms to applied aspects.