Rheumatic fever is an inflammatory disease that can affect the heart, joints, central nervous system, skin, and tissues, typically occurring after an untreated streptococcal infection like strep throat or scarlet fever. It is diagnosed when a patient meets two major criteria or one major and two minor criteria as outlined by the revised Jones criteria, along with evidence of a prior streptococcal infection. Treatment involves preventing further streptococcal infections, anti-inflammatory medications, antibiotics, and bed rest during acute phases of the disease.