The theory behind the Elliott wave is that the forex market will follow a repeatable cycle that includes a major move and a correction.
The theory sates the forex market will make a major movement with five waves and then a corrective move with 3 waves.
The major move on the forex price may be up or down and are numbered from 1-5.

The corrective move on the forex price will be in the opposite direction and are labelled a-c.
Each wave in the forex trend should also be made up of the same 1-5 and a-c waves within each wave.
The most difficult part of interpreting the Elliot Wave in the forex market is correctly determining where a cycle starts and where it ends.