Friction ridge identification, used in law enforcement for fingerprint identification, is based on three premises: (1) friction ridge patterns that develop before birth do not change during life and even after death until decomposition destroys ridged skin; (2) friction ridge patterns differ from individual to individual; and (3) overall friction ridge pattern appearances have similarities that can be systematically classified, even though patterns are distinct in ridge characteristics. Assessing the clarity of fingerprints based on friction ridges involves understanding friction skin development and structure. The friction ridge identification process has two parts, philosophy and methodology. The philosophy stipulates how much detail is required to form an opinion of individuality, while the methodology describes how friction ridge comparison is carried out. Principles and processes of friction ridge identification are compatible with other related forensic sciences. 15 references