Crumpling is signified by the character slowly falling, generally on their knees, before lying flat on their stomach on the ground. Prior to the Street Fighter IV series, opponents would only crumple when knocked out by chip damage, and could not be exploited in gameplay.
Street Fighter IV seriesEdit
The Street Fighter IV series introduced another method of crumpling that had gameplay applications: the Focus Attack.
If a regular Focus Attack hits an opponent mid-attack, the counter hit will crumple them, leaving them open to attack. Level 2 and Level 3 Focus attacks have an inherent crumpling ability, in return for longer charge time. Focus Attack crumples are a popular way to combo into an Ultra Combo.
In addition, certain character's grabs, such as Gen's, will also crumple the foe, though they do not serve any purpose to gameplay in this case.