Gatsby Days are one-day, in-person conferences focusing on the modern website technology stack and the future of web development, featuring presentations from industry experts and Gatsby team members. Held in Mountain View, California, the talks include topics such as the future of website development by CEO Kyle Mathews, the introduction of Gatsby Themes by Chris Biscardi, and the unveiling of Gatsby Preview by Andrew Rhyne. Other presentations cover strategies for selling Gatsby to clients, the evolution of content management with Sam Bhagwat, and effective UX research techniques shared by Shannon Soper. Attendees are encouraged to vote for future Gatsby Days events in their cities, while recordings of the talks are available online for broader access.