Although names can be nested inside classes, the names of global functions, global variables, and classes are still in a single global name space. The static keyword gives you some control over this by allowing you to give variables and functions internal linkage (that is, to make them file static). But in a large project, lack of control over the global name space can cause problems. To solve these problems for classes, vendors often create long complicated names that are unlikely to clash, but then you’re stuck typing those names. (A typedef is often used to simplify this.) It’s not an elegant, language-supported solution.

You can subdivide the global name space into more manageable pieces using the namespace feature of C++. The namespace keyword, similar to class, struct, enum, and union, puts the names of its members in a distinct space. While the other keywords have additional purposes, the creation of a new name space is the only purpose for namespace.