Autoimmune diseases are conditions in which the immune system mistakenly attacks the body's own healthy cells, tissues, or organs instead of protecting against harmful invaders like viruses or bacteria. This misdirected immune response causes inflammation and damage to various parts of the body

. There are more than 80 to over 100 recognized autoimmune diseases, affecting nearly any part of the body. Common examples include rheumatoid arthritis (joints), systemic lupus erythematosus (multiple organs), type 1 diabetes (pancreas), inflammatory bowel diseases (intestines), multiple sclerosis (nervous system), and psoriasis (skin)

. The exact cause of autoimmune diseases is not fully understood but is believed to involve a combination of genetic predisposition and environmental triggers such as infections, chemicals, and lifestyle factors. Women are more commonly affected than men, and having one autoimmune disease increases the risk of developing another

. Symptoms vary widely depending on the specific disease and affected organs but often include fatigue, low-grade fever, joint pain, skin rashes, and general malaise. Treatments typically focus on reducing immune system activity to prevent further damage

. In summary, autoimmune diseases are disorders where the immune system erroneously attacks the body's own tissues, leading to chronic inflammation and damage with diverse clinical manifestations and complex causes