Maybe you're on AMPSport, and there is a long list of Athletes. You want to quickly get to the person you are looking for without scrolling through the whole page.
If you are on Windows:
Hold down the "CTRL" key at the same time as you click the "F" key.
If you are on a Mac:
Hold down the Command key at the same time as you click the "F" key.
Somewhere on the page (depending on your computer) will appear a search field preceded by "Find:" Immediately start typing the name of the Athlete (or other word) you are looking for into that box. You might have to press enter, but it will probably take you immediately to the first appearance of that word on the page. This will work in your PDF viewer and your word processor too. Try it all over your computer!