Can you please define lupus and how does one get lupus?

Autoimmune, systemic: Lupus is an autoimmune disease, in simple terms, your body produces certain antibodies that attack your own organs.It can affect any part of the body. Common symptoms - joint pains, facial rash, photosensitivity, mouth ulcers, hair loss. Organ involvement usually kidney, brain. No one really knows why someone gets it- it is believed that genetic, environmental factors play a major role.