Reverse mentoring involves mentoring that flows from junior to senior employees rather than the traditional top-down approach. It pairs younger employees, who are knowledgeable about social media and technology, with older executives to teach them about these areas. While it provides benefits like keeping executives informed of new technologies, challenges include ego clashes and executives not being open to learning from younger mentors. Successful reverse mentoring programs require clear goals, communication, and training to overcome challenges. Some companies that have implemented it include P&G, where a 30-year veteran began learning from a staff scientist, and the Wharton School, which pairs executives with graduate students as mentors.