The Parent Trap is the title of two movies by Walt Disney Corporation, one made in 1961 and a remake made in 1998. The original 1961 version was followed by three made-for-TV sequels in the 1980s.
In both movies the plot revovles around a pair of identical female twins, who are separated in infancy when their parents separate, each taking one twin with them. In the 1961 original, one twin lives in Boston and the other twin in California, while in the 1998 remake one lives in London and the other in California (the change in locations between the movies is arguably a consequence of increasing globalisation). They meet on a summer camp, where they decide to switch places and then plot to reunite their parents.
Both twins are played by the one actor (Hayley Mills in the 1961 version, Lindsay Lohan in the 1998 version), although this is managed much better in the 1998 version, through the use of computer technology.