Final answer:
Informal feedback is spontaneous and unstructured, and it can come from various sources like peers or colleagues.
Step-by-step explanation:
Informal feedback refers to feedback that is spontaneous and unstructured. It is not typically structured and documented like formal feedback. Informal feedback can come from various sources, such as peers, colleagues, or even subordinates, in addition to supervisors. It is not official and typically not part of performance reviews.