The flexibility of the Wolfram Language's symbolic architecture is reflected in its rich collection of carefully defined constructs for localization and modularization. The use of multiple forms of scoping allows for more elegant, readable and efficient programs, supports the concept of programs as data, and allows direct correspondence with mathematical notions of variables.

With — evaluate with specified variables replaced by values

Module — localize names of variables (lexical scoping)

Block — localize values of variables (dynamic scoping)

DynamicModule — localize names of variables in dynamic interface constructs

Constructs with Automatic Name Scoping

Function — a pure function, with formal variables automatically scoped

Rule (->), RuleDelayed (:>) — named pattern variables automatically scoped

Set (=), SetDelayed (:=) — named pattern variables automatically scoped

Constructs with Automatic Value Scoping

Table — create a table, with iterator variables automatically scoped

Do  ▪  Sum  ▪  Plot  ▪  Plot3D  ▪  NDSolve  ▪  ...

Other Forms of Scoping

Begin, End — localize symbol namespace

Throw, Catch — localize control transfer

Confirm, Enclose — localize exceptions

Quiet, Check — localize messages

BlockRandom — localize pseudorandom variables

WithCleanup — clean up before returning the result of an evaluation