This book underscores the effects of anthropogenic changes on microbes external to us and the consequences of the resultant environmental dysbiosis for our continued health and well-being. Since before the time of our last common ancestor, microbes have been shaping our evolution and our environment, just as we have shaped theirs. This fact has recently gained renewed prominence with wider acknowledgement of the microbiome (part of One Health) and its role in maintenance of human homeostasis. This two-part book titled "Pathogens and Environmental Impact on Life Forms" highlights the fluid dynamics we share with the microbes within us, including both, arguably 'helpful' species, and undoubtedly pathogenic ones (pathogen containment, clearance, and optimisation are dwelt on). Prominent examples include indiscriminate industrialisation and urbanisation. Both of these forces, empowered by a culture of consumerism, have led to excessive pollution and several detrimental lifestyle changes, which have culminated in our present obesity crisis and diabetes 'pandemic'. Finally, this book concludes by emphasising that the way forward for healthcare is not only to be cognizant of the eubiotic microbiome in its diagnoses and treatments, but also to use this tremendous resource to contend with the quickly transforming landscape of infectious diseases.