If you want to learn more about Group Policies then I suggest that you download and read the following documents:
MS-GPSOD]: Group Policy System Overview Document
http://download.microsoft.com/download/C/6/C/C6C3C6F1-E84A-44EF-82A9-49BD3AAD8F58/%5bMS-GPSOD%5d.pdf
MS-GPOL]: Group Policy: Core Protocol Specification
http://msdn.microsoft.com/en-us/library/cc232478(v=PROT.13).aspx
MS-GPDPC]: Group Policy: Deployed Printer Connections Extension
http://msdn.microsoft.com/en-us/library/cc232156(v=PROT.13).aspx
MS-GPEF]: Group Policy: Encrypting File System Extension
http://msdn.microsoft.com/en-us/library/cc232218(PROT.10).aspx
MS-GPFR]: Group Policy: Folder Redirection Protocol Extension
http://msdn.microsoft.com/en-us/library/cc232290(v=PROT.13).aspx
MS-GPIE]: Group Policy: Internet Explorer Maintenance Extension
http://msdn.microsoft.com/en-us/library/cc232356(v=PROT.13).aspx
MS-GPIPSEC]: Group Policy: IP Security (IPsec) Protocol Extension
http://msdn.microsoft.com/en-us/library/cc232415(v=PROT.13).aspx
MS-GPPREF]: Group Policy: Preferences Extension Data Structure
http://msdn.microsoft.com/en-us/library/cc232587(v=PROT.13).aspx
MS-GPREG]: Group Policy: Registry Extension Encoding
http://msdn.microsoft.com/en-us/library/cc232678(v=PROT.13).aspx
[MS-GPSB]: Group Policy: Security Protocol Extension
http://msdn.microsoft.com/en-us/library/cc232743(v=PROT.13).aspx
MS-GPSCR]: Group Policy: Scripts Extension Encoding
http://msdn.microsoft.com/en-us/library/cc232812(v=PROT.13).aspx
MS-GPSI]: Group Policy: Software Installation Protocol Extension
http://msdn.microsoft.com/en-us/library/cc232854(v=PROT.13).aspx
MS-GPWL]: Group Policy: Wireless/Wired Protocol Extension
http://msdn.microsoft.com/en-us/library/cc232934(v=PROT.13).aspx