Namespace is used to refer to a context within which names may be relatively defined; the end result being that two names in different namespaces are distinct and a name should be unambiguously resolved if it is referenced with a fully qualified path of ancestor namespaces.
Systems may layer additional functionality on top of this to facilitate packaging and modularity, but namespace is used to refer to the simple foundation.
The namespace keyword followed by the ::
delimited path of the namespace is used to add definitions to the
indicated namespace (which can subsequently be accessed using their
paths absolutely or byby using a relative namespace).
Namespaces are defined using modules for which declarations are added by enclosing contents within a construct of the form:
module <name> wherewhere where provides latent declaration behavior
analogous to its use elsewhere.