Apollo Day is a live webcast event scheduled on July 16th, broadcasted from Seattle. It will help developers learn best practices and hear talks from experts at Apollo and Expedia about adopting GraphQL for their companies. The agenda includes technical talks, a coffee break, an open Q&A session, and networking opportunities, showcasing new platform capabilities and featuring engineers from Expedia already using GraphQL in production. Attendees can also sign up for the webcast or join in-person in Seattle to learn more about implementing GraphQL best practices and hearing about upcoming platform announcements.