Maybe you’ll never need this one, but sometimes you want to see the actual HTML code used to create a web page.
In Firefox, go to the page you want to view and then press Ctrl+U. A new Window appears with the HTML code visible and colored appropriately.
(In Internet Explorer, you can press Alt+V to open the View menu, then press C to select the Source command. A Notepad window appears with the HTML code available for editing.)
Remember, Alt+F4 closes a window — use that when you’re done looking at the source HTML code.