Forensic Science means any science which is used as evidence in a court of law. It is also taken to mean scientific analysis and comparison used in the detection and investigation of crime.
The word forensic is derived from the Latin adjective forensis meaning "of or before the forum". In ancient Roman society, cases involving criminal charges were presented before a group of individuals in the forum. Both the victim and suspect would give speeches on their side of the story. The best argument would determine the outcome of the case.
Although there are some examples of forensics being employed in antiquity, the idea of using science in the fight against crime didn't become popular until the late Middle Ages due to the frequency of human poisonings across Europe. Poisoning was difficult to detect because the symptoms were similar to those of many of the untreatable infectious diseases of the time. At the beginning of the 19th century, the first steps were made to demonstrate the use of poison by analysing the corpse for toxic substances.
Towards the end of the 20th century, the acceptance that everybody has different fingerprints made a great impression on the detection of crime, as did the discovery that people have different blood groups, so that blood stains left at a scene or found on an injured party could be linked to a suspect.
Forensic Science has been greatly popularised by authors such as Sir Arthur Conan Doyle, through his infamous character Sherlock Holmes, and through many contemporary TV series such as CSI, Dexter and Bones. It has also created unrealistic expectations from forensic science known now as the "CSI Effect"!