Here's a link to info on using iframes - they're a more 'Healthy' alternative to 'Frames', and rather easier to use. Beware of accessibility issues though among other things, and in no way are Iframes good to use gratuitiously ...
Iframes display a web page within another - in the same way that a web page might display an image ... Here's one, by default it displays the Bath Spa University library catalogue - it's a web page so it's fully functional:
You can target the frame to load other pages from links as follows:
Mark Annand • Site updated May 10th 2012