http://blogs.technet.com/chitpro-en/archive/2009/04/02/ifilters-for-microsoft-office-sharepoint-server-2007-or-windows-desktop-search.aspxQuite often, customers and partners ask about iFilters. For those who don’t know what an iFilter is, well, when a Indexing Service needs to index the contents of a file, it needs to know what the format of the file is. A PDF file has a different formaten-USCommunityServer 2.1 SP1 (Build: 61025.2)