Urinary tract infection (UTI) refers to the inflammation caused by the growth and reproduction of pathogens in the urinary tract and the invasion of the urinary tract mucosa or tissue. It is the most common type of bacterial infection. Urinary tract infection is divided into upper urinary tract infection and lower urinary tract infection. Upper urinary tract infection refers to pyelonephritis, and lower urinary tract infection includes urethritis and cystitis. According to the presence or absence of underlying diseases, urinary tract infection can also be divided into complicated urinary infection and uncomplicated urinary infection. Pyelonephritis is further divided into acute pyelonephritis and chronic pyelonephritis. It is more common in women. Its clinical manifestations are often: acute urethral syndrome, chronic urethral syndrome, asymptomatic bacteriuria, renal abscess and perinephric abscess. Among them, urinary tract infections caused by different pathogens include: chlamydial urinary tract infection, mycoplasma urinary tract infection, fungal urinary tract infection, and parasitic urinary tract infection. Urinary tract infections in different populations include: menopausal urinary tract infection, pediatric urinary tract infection, elderly urinary tract infection, postpartum urinary tract infection, and pregnancy urinary tract infection.