The FAQ includes such topics as:
NLS_LANG Parameter Fundamentals
Checking the current NLS_LANG Settings
How to setup the NLS_LANG Property for UNIX
Where to set the NLS_LANG in Windows
A Whole Pile of Other Frequently Asked Questions
Check out the NLS_LANG FAQ if you’re looking to learn about the NLS_LANG and associated settings or to find the answers to many common questions on these parameters.