Leaving the scene of a web page for the scroll function of the mouse can be a waste of effort. Why isn't there a scroll wheel on the keyboard? Well, a very select few come with a built-in scroll wheel, but it's usually just a justification of adding to the price of a relatively high-profit-margin item already. What if I told you there was a scroll wheel already built-in to your keyboard? The humble spacebar is coded to act as a fast scroll in Safari, Firefox, and many other Mac applications. When viewing a page that's longer than the window, just tap the spacebar and it'll jump--useful for scrolling a long window quickly.
As our intrepid Windows users may already know, the full-size keyboard contains many useful keys for quick navigation of documents, web pages included. The "home," "end," "page up" and "page down" keys are there as relics from the pre-mouse days when most of what was done on a computer took the form of long pages of various lines of text or code. But there's more! The arrow keys are another multi-directional scroll entry point. Left, right, up and down, they will scroll through documents big and small! However, the space bar is placed in a location that allows for a fast click down a page, whereas the other keys require hand movement, something I strive to avoid as much as possible. A word of caution: the space bar works as a space bar in t e x t d o c u m e n t s , b u t f o r o t h e r a p p l i c a t i o n s , s p a c e a r o u n d ! ! ! [Britt Godwin]
