In the 8years since the publication of the 4th edition of the WHO Classification of Hematopoietic and Lymphoid Tumours in 2008, there has been rapid accumulation of knowledge in the molecular genetics, biology, clinical behavior of many hematologic malignancies. Concepts and models have advanced to the point at which updates were deemed necessary prior to the formal WHO process of publication of a 5th edition as part of the WHO blue book series. This overview will focus on lymphoid tumors and highlight important changes and updates to these neoplasms.