Answer
Namespaces can be nested to reflect module structure. C++17 added a compact syntax using :: to declare nested namespaces in one line, avoiding multiple nested braces. Names are accessed with the full qualified path (outer::inner::name).
namespace a::b::c { // C++17 nested shorthand
int x;
}
int y = a::b::c::x;Real-world example A project uses nested namespaces like company::product::detail to organize its code.