Setting Base properties
Use the Base element to set the base URL that all document-relative paths in the page are considered relative to.
Href is the base URL. Click the Browse button to browse to and select a file, or type a path in the text box.
Target specifies the frame or window in which all linked documents should open. Select one of the frames in the current frameset, or one of the following reserved names:
_blank loads the linked document in a new, unnamed browser window.
_parent loads the linked document into the parent frameset or window of the frame that contains the link. If the frame containing the link is not nested, then this is equivalent to
_top; the linked document loads into the full browser window.
_self loads the linked document in the same frame or window as the link. This target is the default, so you usually dont have to specify it.
_top loads the linked document in the full browser window, thereby removing all frames.