Marginalia is a search engine that prioritizes non-commercial content and uses custom index and crawler software. It aims to provide a way to find interesting things on the 'small web' and does not intend to compete with major search engines like Google or Bing. The project is open-source and has been developed by one person, with a goal of maintaining operations with minimal costs and relying on grants and public donations. The search engine uses a simple technology with no AI and filters out tracking, with no data shared with third parties.