File System Filter Manager :What is this for?

I have noticed many times File System Filter Manager but I am not knowing what are the programs that are depended on this File System Filter Manager. I know that it is used by anti-virus programs and some other program also. Can any one tell me what is this for? Thank you in advance for your valuable suggestions.

I want to know whether any one was able to get file system filter manager working on windows xp installation pack without any pack? I have installed the driver for it through the inf file but I think it does not seem to load on bootup and it is not even starting. When start windows with boot log it does not show any additional information and the driver is not listed.I do not have any idea whether this file file system filter manager is suppose to work without any service pack. I think this is delivered with windows service pack 2. however I thought just to clear it whether file system filter manager works on windows xp(Without service pack) or not.

Filter manager is a file system filter driver that is offered from Microsoft which simplifies the creation of third party filter drivers and has resolved many of the issue with the existing functionality. anti-virus filters, backup agents, and encryption products are the example of file system filter drivers. You can use IFS Kit provided by Windows Driver kit to create file systems and file system filter driver.A filter driver developed to the Filter Manager model is called a minifilter. Each minifilter has an attribute associated with it which determines whether minifilter is loaded relative to other in the Input/Output stack.

I have downloaded vlite version 0.8 and when I try to run vlite it says that I need to install file system filter manager. I stick to my original copy of windows xp and it keep on displaying message saying that wrong CD or file system filter are not present. I am totally lost and confused about this but I want to continue using my vlite. If you have any suggestions so that I can use my vlite again, please let me know. Your valuable suggestions would be appreciated.

Purpose of filter manager is to just simply write file system filters and it also sometime does this by abstracting some of the thing that is needed by filter to deal with it.Some of the internal Fltmgr structure are not accessible to the developer still they can display in debugging.
Name: Fltmgr.sys
size: 105.472
version: 6.0.4015.0
Company: microsoft corporation.
Desc.: Microsoft file system filter manager