$MachineAddresses (Built-in Mathematica Symbol)

$MachineAddresses gives a list of strings specifying the current IP addresses associated with the computer on which Mathematica is being run.

$MachineID (Built-in Mathematica Symbol)

$MachineID is a string that gives, if possible, a unique identification code for the computer on which Mathematica is being run.

$MachineName (Built-in Mathematica Symbol)

$MachineName is a string that gives the assigned name of the computer on which Mathematica is being run, if such a name is defined.

$MaxMachineNumber (Built-in Mathematica Symbol)

$MaxMachineNumber is the largest machine-precision number that can be used on a particular computer system.

$MaxNumber (Built-in Mathematica Symbol)

$MaxNumber gives the maximum arbitrary-precision number that can be represented on a particular computer system.

$MessageGroups (Built-in Mathematica Symbol)

$MessageGroups is the list of rules that gives named message groups used in functions like On and Quiet.

$MessageList (Built-in Mathematica Symbol)

$MessageList is a global variable that gives a list of the names of messages generated during the evaluation of the current input line.

$MessagePrePrint (Built-in Mathematica Symbol)

$MessagePrePrint is a global variable whose value, if set, is applied to expressions before they are included in the text of messages.

$MinMachineNumber (Built-in Mathematica Symbol)

$MinMachineNumber is the smallest positive machine-precision number that can be used on a particular computer system.

$MinNumber (Built-in Mathematica Symbol)

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