Dear Editor, Bacteria are traditionally categorized into two broad categories of pathogenic and non-pathogenic. Many infectious diseases in humans and animals are caused by pathogenic bacteria, including respiratory, gastrointestinal, genitourinary, and central nervous system infections, as well as plant infections. Therefore, they are wellknown. However, only a minority of bacteria species are pathogenic. This category includes free-living, commensal, and probiotic bacteria, which are beneficial for the body. Hence, wenaturally tend to the latter and try to avoid the former. But does this categorization work properly always? In another word, are all Pathogens in the first category harmful? While those in the second category are completely safe? Furthermore, should Pathogens socially be pictured as absolute evils while non-Pathogens are addressed as pure angels? We discussed this issue shortly to clarify the actual missions of the bacteria in life...