Inflammation is defined as a complex local response of living vascularized tissues to injury due to any agent. It is the response of body defense mechanisms to limit or eliminate the agent causing injury. It mainly consists of responses of blood vessels, leucocytes and connective tissue. This chapter describes types of inflammation, local pathological events, systemic inflammatory response occurring during acute inflammation and its outcome. Acute inflammation is of short duration and there is early body reaction followed by repair. Chronic inflammation is of longer duration. Either agent causing acute inflammation persists for a long time or stimulus is such that it causes chronic inflammation from the beginning. Chemical mediators of inflammation are briefly outlined in a box. Basic functions of inflammatory cells and chronic inflammation are also described.