Inflammation is a condition or a response of the body caused by an injury or infection. It may be included as a reparative process of an injured tissue. During inflammation, the affected part of the body may become swollen, erythematous, hot, and painful. It is a natural response of the body against injuries and infection. It is employed by the body to protect the body by preventing the infection from further spreading and for making the site more permeable to immune cells that can remove pathogens and dead cellular debris. Inflammation that is accompanied by suppuration is called suppurative inflammation. When inflammation does not involve pus formation it is said to be nonsuppurative.
In suppurative inflammation, there is a purulent exudate at the injured site. The purulent exudate (synonymous to pus) forms as a result of the action of polymorphonuclear leukocytes (e.g. neutrophils) against pathogens (e.g. bacteria) and their liquefaction of necrotic tissue elements. Thus, the purulent exudate in the inflamed body part is characteristically thick, and may vary in color depending on the pathogen causing the infection. Because of this, suppurative inflammation is also called purulent inflammation.