Scope

A collection of identifier bindings – i.e., what is captured by the Environment at some point in the code or in time.

Nested

With nested scopes, variables in inner scopes may shadow those in outer scopes, and variables are removed as control flows out of the scope. Variable shadowing may be forbidden in some languages.

Named

With named scopes, we can refer to names in scopes that are not ancestors of the current scope. For example, with C++ classes and namespaces and Java packages and (static) classes.

[Wikipedia]