The Topic Index consists of a list of web pages, one for each topic or specific subject of The Urantia Book, that collects all the relevant information that appears in the book on that topic.
Topic pages are attempted to be automatically linked when uploading content from The Urantia Book or the Bible using the Urantiapedia Tools software, which is responsible for creating those pages.
Some examples of topics could be concepts like absonity, or people like Grandfanda, or types of beings like Thought Adjusters, or places like Nazareth or Orvonton, or events like the arrival of Adam and Eve, etc.
There is currently a catalog of more than 4,000 topics created, and a first version of them in Spanish and English is in the process of being created. Once this first version is finished in those languages, an appropriate technical mechanism will be put in place to make it easy the translation into the rest of languages.
To learn more about how Topic Index is organized in the project, check out Urantiapedia Help.