A ghost step is a type of lead that hides its initiation. These are similar to Force Leads but use a more advanced understanding of the disparity between Parallel Motion Leads,Change of Frame Leads to create initiations that seem to come from no where.
These are a more advanced type of initiation that often simply results in force leads among the inexperienced. A proper ghost step requires a strong grasp of both types of lead as well as validation, proprioception, Timing and usually Rotational Mechanics.
The fundamental idea is that with both an danced lead and follower you can initiate Parallel Motion Leads over a small amount of space. This maximizes the amount of time for Change of Frame Lead and Validation over the play out of the momentum generated.
With practice this can turn into a small Weight Shift without a step combined with a Change of Frame Lead creating a large motion for the follower or even perpetual follow motion.