A replica is a copy that is relatively indistinguishable from the original. Replicas are often used for historical purposes, such as being placed in a museum. Sometimes the original never existed. For example, Difference Engine No. 2, designed by Charles Babbage in the 19th century, was reconstructed from original drawings studied by Allan Bromley in the 1980s and is now on display at the Science Museum in London, England. A second example is Stephenson's Rocket where a replica was built in 1979, following the original design fairly closely, but with some adaptations.
However, replicas have often been used illegally for forgery, counterfeits, fakes especially of money & coins, but also commercial merchandise such as designer label clothing, luxury bags & accessories, and luxury watches. In arts or historic cars, the term "replica" is used for a non-original recreation, sometimes hiding its real identity.
One definition of "replica" has emerged that defines one as a copy of an original object, that can only be made by the original company (or corporate descendent) of the firm that made the original object-any other sort of copy of an original object would be called a "reproduction" instead.
Because of gun ownership restrictions in some locales, gun collectors often create non-functional legal replicas of illegal firearms. Such replicas are also preferred to real firearms when used as a prop in a stage performance, generally for safety reasons.