ABS Exercise is a type of exercise that focuses on strengthening the abdominal muscles. Situp and CRUNCH are two common exercises used to target the abs. A situp is an exercise where one lies on their back and lifts their upper body off the ground, while a CRUNCH is an exercise where one lies on their back and lifts their upper body off the ground while keeping their legs stationary. Both exercises are effective in strengthening the abdominal muscles.