A mach-cut is a cut between two shots which match graphically. This match establishes a sense of continuity and interconnectedness between two different spatial or temporal spheres (space and time). The matching between a shot Z and shot X tends to produce a sense of importance in the connection. The match cut is an editing technique which imbues the different spheres with a sense of metaphor or symbolic relationship. If shot Z has a violent connotation and is matched with X then the action of X will also be imbued with that violent connotation [Although a part of the continuity editing style the match cut is linked to and could be argued inspired by, the montage style and theory of parallelism].
In the beginning of the film Strangers On A Train (1951) we see two different pairs of shoes walk towards a train. The two characters’ footsteps are linked together by a match cut which indicates an inevitable meeting and connection between the two characters’ fate. Essentially the characters are walking the same “footsteps” towards a linked fate. The match cut is primarily a graphic or visual connection between two different spatial or temporal locations. The second function is metaphorical or symbolic and a tool in which to produce meaning by matching two ideas together producing a synthesis of major importance. 2001: A Space Odyssey(1968) matches the throwing of a bone to a space station. The throwing of a bone, after the use of it as a weapon, indicates a leap forward towards humanity [evolution] and a movement forward in scientific progress and the use of tools. These concepts are linked to the space station firstly as the station itself is a tool as such and an indicator of scientific progress but also in larger context of the film as the technology of the space station is a movement towards another leap in evolution: that of artificial life.