$FrontEndSession (Built-in Mathematica Symbol)

$FrontEndSession is a global symbol that represents the current session of the front end from which the kernel is being run.

$GeoLocation (Built-in Mathematica Symbol)

$GeoLocation is a settable global variable that specifies the default geodetic location to use.

$ImportFormats (Built-in Mathematica Symbol)

$ImportFormats gives a list of import formats currently supported in your Mathematica system.

$Inspector (Built-in Mathematica Symbol)

$Inspector is a global variable which gives a function to apply when the inspector is invoked from an interrupt menu.

$IterationLimit (Built-in Mathematica Symbol)

$IterationLimit gives the maximum length of evaluation chain used in trying to evaluate any expression.

$LicenseExpirationDate (Built-in Mathematica Symbol)

$LicenseExpirationDate is a date list that gives the expiration date for the license under which Mathematica is being run.

$LicenseID (Built-in Mathematica Symbol)

$LicenseID is a string that gives the license ID under which Mathematica is being run.

$LicenseServer (Built-in Mathematica Symbol)

$LicenseServer is a string that gives the name of the license server that is currently authorizing Mathematica to be run.

$Line (Built-in Mathematica Symbol)

$Line is a global variable that specifies the number of the current input line.

$Linked (Built-in Mathematica Symbol)

$Linked is True if the Mathematica kernel is being run through MathLink.