Lymphoma can be broadly defined as a cancer of mature lymphocytes. Our understanding of the biology of normal lymphocytes and lymphoma has grown at a tremendous pace, and this is now directly translating into changes in clinical practice. This became evident with the introduction of one of the first therapeutic monoclonal antibodies into cancer medicine, the CD20-directed antibody rituximab, which has led to significant benefit for patients with B-cell lymphomas. Since then, a raft of novel agents has entered clinical practice, including targeted small molecules, antibody-drug conjugates, bispecific antibodies, and chimeric antigen receptor (CAR) T cells. This new edition of 'Fast Facts: Lymphoma' has been updated to include recent changes in our understanding of lymphoma biology as well as improvements in diagnostics and therapeutics.