In the standard notebook front end, Mathematica allows you to set a large number of global options. The values of all these options are by default saved in a "preferences file", and are automatically reused when you run Mathematica again. These options include all the settings which can be made using the Preferences dialog.
|style definitions||default style definitions to use for new notebooks|
|file locations||directories for finding notebooks and system files|
|data export options||how to export data in various formats|
|character encoding options||how to encode special characters|
|language options||what language to use for text|
|message options||how to handle messages generated by Mathematica|
|dialog settings||choices made in dialog boxes|
|system configuration||private options for specific computer systems|
You can access global front end options from the kernel by using Options[$FrontEnd, name]. But more often, you will want to access these options interactively using the Option Inspector in the front end.