Feedback is critical because it allows the receiver to discover specific ways to improve, directs learning and serves as a motivating force. Although some people perceive it as criticism, quality feedback can improve the receiver's ability to achieve the set goals.
Unlike learning general principles, feedback is work-specific. When specific feedback is given, the receiver is able to see areas in her own process that can be improved. This removes the theoretical element of general principles and becomes something concrete that the receiver can both understand and see the need for.
The best feedback provides suggestions for the individual to improve her performance. This can significantly speed up the learning process, while giving the receiver an opportunity to immediately implement whatever skills they have learned.
Positive feedback, or remarks given to praise portions of the receiver's work, can generate a sense of accomplishment in the individual. Once she experiences that, she will want to replicate the feeling by producing more work that merits positive feedback. Thus, it motivates the individual to continue improving her performance.
Ultimately, feedback provides an opportunity for the receiver to understand how another person perceives her work and learn new ways she might be able to achieve her goals.