Some templates allow you to include static parts, e.g. in the footer or elsewhere.
I use this to ad a notification banner on top of my web site to tell them that we moved to a new domain (in German, sorry, but you get the idea).
How to use this differs from template to template, so you better check with the template documentation if that is possible. As for how it is done on my site, I use this opportunity to shamelessly advertise my own template, which has this feature and I believe it is well documented on the info page as well :-)