The @blurb directive sets a tooltip for the page which is displayed when hovering over an image link to that page. So for example the 2001 page has at the top:

  @blurb		Utah Florida and the Peak District

and when hovering long enough over the image link to 2001 on the Diary page this tooltip will be displayed.

The tooltips are implemented using CSS, with a transition so they don't appear immediately.