Rapid Cancel is a game mechanic in the Street Fighter series.
Rapid Cancels allow characters who have access to the mechanic to immediately cancel into another attack (similarly to a Target Combo). Unlike Target Combos the initial attack does not have to connect to initiate a Rapid Cancel.
The purpose of Rapid Cancels is to allow a character to more easily link normals, an example is if a MP is +6 on hit, then a LP has a 5-frame startup, rapid canceling would allow the player to instead of having to time the link all that can be done is use the followup attack after the initial one hits
Another purpose is to allow normals that would normally not connect to combo. It has to be noted that some attacks are only meant to link to another (an example is Ibuki's Cr LK to Cr LP as shown in the example).
CPS1 Chains Edit
Main article CPS1 Chain Edit
CPS 1 Chains are a consequence of the original mechanic in The World Warrior. Combos were not originally intended and CPS 1 chains allowed for combos that would otherwise not be possible. They were kept until Hyper Fighting and removed in the start of the CPS2 series with New Challengers.