Abstract: Sepsis is not equal to infection. It is defined as life-threatening organ-dysfunction caused by a dysregulated host response to infection. Sepsis focuses on organ dysfunction instead of the infection, which is the main difference of opinion between Infectious Disease Society of America(IDSA) and Surviving Sepsis Campaign(SSC). Screening is the most important thing for sepsis in order to initialize the sepsis therapy-bundles to improve the patients' outcome. The definition and concept of sepsis originate from the evidence-based medicine and big data study. The methodology of sepsis keeps its development potential. This article interpreted the essence of sepsis to support SSC and disprove the opinions of IDSA.