This document discusses urinary catheterization including purposes, necessary equipment, preparation of the patient, insertion procedure, care of indwelling catheters, and removal of indwelling catheters. Catheterization is used to relieve urinary retention, obtain urine samples, and empty the bladder before surgery. The proper size of catheter depends on patient age and sex, with 14-16 French for females and 18-20 French for males usually being appropriate. Care of indwelling catheters involves cleaning the patient, maintaining fluid intake, recording intake/output, and monitoring for signs of infection.