Different from namespaces, scope rules the declarations the computer can look up at a particular point in the translation unit. Scope does not have anything to do with access control which can deny the usage of a declaration if it’s for example private or protected in programming languages that you can set access control.

Declarations

A declaration introduces names (which include identifiers or non-identifiers) into a namespace (an existing classification or arbitrary grouping defined by a programmer).

By arbitrary means it can take up many forms for different purposes.