What are the five characteristics or signs of infection?

The five classic signs of infection are redness, heat, swelling, pain, and loss of function. Redness and heat occur due to increased blood flow to the affected area, while swelling results from the accumulation of fluid and immune cells. Pain is typically caused by inflammation and irritation of surrounding tissues, and loss of function can manifest as decreased mobility or impaired function of the affected area. These signs indicate the body's immune response to an invading pathogen.