**1. Introduction**

Sepsis and septic shock are life-threatening conditions that remain an enormous burden of morbidity and mortality to millions of patients globally and cause organ dysfunction, leading to death in as many as one in four patients, often even more [1]. Early management and appropriate treatment are essential to improve outcomes and reduce morbidity and mortality.

Sepsis is a multifaceted disorder, developing from a dysregulated response by the host to an infectious nidus, and is associated with acute organ dysfunction and a high risk of mortality.

The incidence of sepsis is high, and remains one of the leading causes of death worldwide [2]. The reported incidence is increasing, which is likely a reflection on the older population with more comorbidities. Even though incidence is not known, estimates indicate that sepsis is a leading cause of morbidity and mortality globally. Even though sepsis is a deadly disease, data now shows the after effects of sepsis to be quite traumatic; often showing long term physical, physiological and cognitive disabilities [3].

Over the past 30 years, with the help of an extensive amount of research and better-quality clinical processes, the treatment and recognition of sepsis has

happened at a faster pace [2]. At the World Health Assembly in 2017, the World Health Organization (WHO) made sepsis a global health priority and passed a resolution to improve the prevention, diagnosis and management of sepsis [4].

In this chapter, we will examine the current definitions of sepsis and septic shock. We will explore the current guidelines in the diagnosis of sepsis. As we delve into the diagnosis, we will discuss the pathophysiology, clinical presentation, risk factors, etiologies, and finally, management strategies and treatments of the adult, pregnant and pediatric populations.
