Publishers define relationships between their own content items (e.g.,
World Wide Web pages) and content items created or maintained by other
publishers. A central namespace manager provides grouping labels that
publishers insert into their content items. Content items having matching
grouping labels are identified as related. Different classes of grouping
labels can be used to define different types of relationships, and
multiple classes of grouping labels can co-exist. Grouping labels are
made available to an information server such as a search server, which
uses the labels in identifying content items related to a currently
displayed content item.