The motherlode of these operators is the Google Hacking Database (GHDB). The GHDB is a community-driven collection of thousands of search queries, carefully crafted to find specific types of sensitive information exposed on the web.
An "index of" page is a dynamically generated web page created by a server when an index file—such as index.html or default.asp —is missing from a directory. When a user navigates to such a directory, the web server automatically generates a simple page that lists all files and subfolders within that directory, essentially creating a raw file index rather than a formatted webpage. This feature can be observed with many server configurations; a directory listing will look similar to what you'd get from a command line, displaying an index of files, their sizes, and modification dates. index of acrobat pro