Suppose you were on a site that had some Hebrew text, and you wanted to see that text in transliteration. Wouldn't it be convenient if your browser had a button that automatically transliterated any text that you selected? That's exactly what these "bookmarklets" are for.
Below, there are several links that say "Transliterate." These are not normal links. Don't click them; that's not how they work.
Got it? OK, go ahead and drag one of these links into your browser's "links" bar: