In general, a namespace is an abstract container providing context for the items (names, or technical terms, or words) it holds and allowing disambiguation of items having the same name (residing in different namespaces).

As a rule, names in a namespace cannot have more than one meaning, that is, two or more things cannot share the same name. A namespace is also called a context, as the valid meaning of a name can change depending on what namespace applies. Names in it can represent objects as well as concept, whether it is a natural or ethnic language, a constructed language, the technical terminology of a profession, a dialect, a sociolect, or an artificial language (e.g., a programming language).

For many programming languages, a namespace is a context for identifiers. In an operating system, an example of namespace is a directory. It contains items which must have unique names. In the Java programming language, items that appear in namespaces have a short (local) name and unique long "qualified" names for use outside the name space. Also, some languages (such as C++) combine namespace and names in a process called name mangling in order to eradicate ambiguity.