TraditionalFunctionNotation is an option for selections that specifies whether input of the form f(x) is interpreted by the kernel as a function or as a product.
$Display gives a list of files and pipes to be used with the default $DisplayFunction.
$PerformanceGoal gives the default setting for the option PerformanceGoal for graphics and other algorithmic functions.
$SoundDisplayFunction gives the default setting for the option DisplayFunction in sound functions.
$SystemCharacterEncoding gives the default raw character encoding for the computer system on which Mathematica is being run.
Mathematica uses its symbolic architecture to provide a convenient modular framework for generating and managing messages, both in programs and interactive sessions.
DiacriticalPositioning is an option for UnderscriptBox and related boxes that specifies how close diacritical characters are drawn to the base character.
OptionInspectorSettings -> {opt_1 -> val_1, opt_2 -> val_2, ...} is a global option that specifies the display of options in the Option Inspector.
VerifyConvergence is an option to Sum, NSum, and similar functions that specifies whether convergence checking should be done.
$DateStringFormat gives the default format to use for date strings generated by DateString.