Drupal Lite 7: Link to Pages on Your Site (Internal Hyperlinks)
Internal hyperlinks are links within your site-- for example, from a project page to a researcher’s biography page. The link tool will create relative references for the links. The primary benefit is that the link will be accurate even if the page title or URL changes.
The default behavior is to open links in the same window. You can change the behavior of the link using the Target option.