based on an earlier version of the Wolfram Language.
Mathematica is to its core a fundamentally extensible system, in which efficient, modular, reusable packages of any size can readily be created. Mathematica's symbolic program and interface architecture allows it to provide a uniquely flexible modern software development environment with many important original features.
Module — localize names of variables
Block — localize values of variables
DynamicModule — localize interface constructs
Needs — load a package if needed
Save — save definitions for symbols & functions
SyntaxInformation — specify automatic syntax annotation
Initialization Cell — define a cell to be used as initialization
Notebook History — show editing history of a notebook
MathematicaScript — run standalone executable scripts
$ScriptCommandLine — script command-line arguments