Indexing Service is no longer supported as of Windows XP and is unavailable for use as of Windows 8. Instead, use Windows Search for client side search and Microsoft Search Server Express for server side search.
The Filtering component coordinates filtering of files. Its output is called a word list. This component is called by the Indexing component.
The CiDaemon.exe file contains the Filtering component. One executing instance of CiDaemon.exe exists for each Indexing Service catalog.