This is a feature particular to FrontPage. If you have a group working on a web site, or you want to have several sites with different styles on one web domain (or account), FrontPage allows you to create a web inside of another web, and a web inside of a web inside of a web. Each 'subweb' also has its own set of permissions, its own username and password, and its own shared borders and configuration files.
A named subdirectory of the root web that is a complete web. Each subweb can have independent administration, authoring and browsing permissions from the root web and other subwebs. Any number of subwebs can be created under the root web, and subwebs can be created within subwebs. See also root web, web.