Forensic science is any science used to explain impartially and scientifically any evidence considered in both civil and criminal courts of law, as well as in related investigations.  Forensic science is a multidisciplinary subject, drawing principally from chemistry and biology, but also from physics, geology, psychology, social science and other fields.

In a typical criminal investigation, crime scene investigators will gather material evidence from the crime scene, victim and suspect.  Forensic scientists examine these evidentiary materials and render a scientific explanation, based on analysis, for the purpose of providing scientific evidence to assist in the law enforcement investigation and any subsequent trial court proceedings. Senior forensic scientists, who usually specialize in one or more of the key forensic disciplines, may be required to attend crime scenes or give evidence in court as impartial expert witnesses.