FileExtension["file"] gives the file extension for a file name.

LinkPatterns[link] gives a list of the patterns for which definitions were set up when the external program associated with the specified MathLink connection was installed.

$CurrentLink is the LinkObject representing the MathLink connection for an external program currently being installed or being called.

X Environment Information opens a dialog box that displays the current attributes of the X front end environment (X only).

OperatingSystem is an option for file and related operations that specifies the type of operating system to use to determine file name and other conventions.

$Context is a global variable that gives the current context.

To run Mathematica using a network license, both the client machine and the license server must be on the network and MathLM must be running. If you do not have a MathLM ...

When exchanging expressions with external programs, the Mathematica kernel uses the convention of wrapping the expressions inside packets which identify what role the ...

Mathematica stands out from traditional computer languages in supporting many programming paradigms. Procedural programming is the only paradigm available in languages like C ...

<< name reads in a file, evaluating each expression in it, and returning the last one.