How to quickly scroll through a long web page or document in OS X

How to quickly scroll through a long web page or document in OS X

When you’re browsing a long web page in Safari or reading a PDF in Preview app, you can use the Page Up and Page Down keys to move roughly one page up or down for quick and easy reading.

But most keyboards in the MacBook or Apple Wireless Keyboard do not come with Page Up and Page Down keys.

Instead you use Fn-Up Arrow (Fn key together with Up Arrow) for Page Up, and Fn-Down Arrow for Page Down.

Or you can use Space key for the Page Down, and Shift-Space key for the Page Up.