Scope
In plain terms
The region of a program where a name is accessible.
Going deeper
Scope defines where variables and functions can be referenced, controlling visibility and lifetime. It determines what's in reach.
Under the hood
Lexical (static) vs. dynamic scope; nested scopes and closures capture surrounding variables.
Examples
Local/global scope, closures, block scope, variable visibility, namespaces.
Think of it like...
Like rooms in a house, what's in one room isn't visible from another unless shared.