[musicale]

Scroll lock mode (arrow keys scrolling the window rather than moving the cursor) is almost identical to the way the arrow keys work to scroll a web page – a sort of keyboard equivalent to using a mouse scroll wheel or 2-finger scrolling on a trackpad. It's particularly nice in that it scrolls a single row or column at a time, and particularly useful for spreadsheets (Excel) and text editors.

I currently have a compact ("tenkeyless") keyboard which lacks the key, so I tend to use a spring-loaded setup where holding down alt/option/etc. and an arrow key scrolls the window.