Gatsby, recognized as a top technology to learn in 2020, is featured in the #100DaysOfGatsby challenge, encouraging both beginners and experienced users to explore its features and ecosystem. Challenge 14 focuses on utilizing and creating Gatsby Themes, which function as customizable website kits that can be shared and combined to enhance site development. Participants are guided through the philosophy and practical use of Gatsby Themes, with resources including insights from experts like Kyle Mathews and Chris Biscardi, as well as examples from the Apollo team. The challenge provides a step-by-step guide on using themes with a "shadow and extend" approach, and offers community support through platforms like Discord and Twitter. This initiative is aimed at empowering users to leverage Gatsby's capabilities for building efficient and performance-optimized websites.