Diffuse Large B-Cell Lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma (NHL), representing about 30-40% of all NHL cases. It is a fast-growing cancer that originates in the B-lymphocytes, which are a type of white blood cell responsible for producing antibodies. This aggressive form of lymphoma can arise in lymph nodes or other organs, making early detection and treatment crucial.