Standardization of definitions has been considered important in sepsis to facilitate accurate diagnosis and treatment, to clarify patient inclusion criteria for clinical trials, and to enable comparison of results from different studies. However, despite development and publication of consensus conference definitions, diagnosis of sepsis remains difficult in clinical practice and many patients do not receive the early specific therapy that could benefit them. Concepts of sepsis need to evolve such that good global definitions are accompanied by better strategies for individual diagnosis and disease characterization; patients can then be treated rapidly and appropriately to maximize their chances of survival.