I am every time confused about the functioning the "scroll lock" key

The use of this key was lost years ago, frankly, unless you're still a super adept of keyboard usage in Excel and whatnot.

There are a few obsolete systems that always used that for a few functions, but the most well known is for Excel and some older spreadsheet programs. It's used so that you can move the page without moving away from the selected cell.

On Excel for example, assuming you have used it, if you use the arrow keys you will move across the cells, right? If you have Scroll Lock on, the sheet instead will move and the selected cell with remain the same. Feel free to try it.

That's about it really, when it comes to modern day PCs, unless there is other software out there that also makes use of this change, but I wouldn't really know anything about those.

Really I too did not know about its usage and I wondered why it was there. Looking this discussion enlightened me. Thanks!