Gatsby, a popular technology to learn in 2020, offers a #100DaysOfGatsby challenge to help individuals explore its ecosystem, whether they are newcomers or experienced users. Challenge 15 of this initiative focuses on creating a Gatsby Theme, a way to package site development work for use by others, promoting sharing within teams or the open-source community. Participants are encouraged to utilize resources such as a free video course and a written guide, alongside exploring projects from the Theme Jam hackathon for inspiration. Assistance is available from the Gatsby community through various platforms, including Discord, Reddit, and Twitter, and participants are invited to share their progress on social media.