$BatchOutput (Built-in Mathematica Symbol)

$BatchOutput is True if output in the current session is being sent in batch mode, suitable for reading by other programs.

$CharacterEncodings (Built-in Mathematica Symbol)

$CharacterEncodings gives the list of character encodings that can be used.

$FrontEnd (Built-in Mathematica Symbol)

$FrontEnd is a global variable that specifies to what front end object, if any, the kernel is currently connected.

$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.

$KernelCount (Built-in Mathematica Symbol)

$KernelCount gives the number of subkernels available for parallel computations.

$MinNumber (Built-in Mathematica Symbol)

$MinNumber gives the minimum positive arbitrary-precision number that can be represented on a particular computer system.

Manipulating Integrals in Symbolic Form (Mathematica Tutorial)

When Mathematica cannot give you an explicit result for an integral, it leaves the integral in a symbolic form. It is often useful to manipulate this symbolic form. ...

$CUDALinkPath (CUDALink Symbol)

$CUDALinkPath is the path to the CUDALink application.

OpenSQLConnection (DatabaseLink Symbol)

OpenSQLConnection[src] makes a connection to a data source.OpenSQLConnection[] opens a GUI that helps to make a connection to a data source.

SQLServer (DatabaseLink Symbol)

SQLServer[...] is an object that represents a server process started in Mathematica.