This document summarizes Marianne Bellotti's experience with and advice about hackathons. It discusses that hackathons are beneficial for networking, meeting influencers, learning new skills and technologies. While large events have more recognition, smaller events have a better atmosphere for bonding and mentoring. The API Hack Day event, despite seeming unpromising, proved most profitable due to the quality of people met. The summary encourages attending hackathons to build connections, skills in areas like leadership and presentations, and advises focusing hacks on a compelling core idea and demo. It provides examples of Marianne's successful hacks and prizes won at various events.