Paging lists of results

Reddit (I only read it for the articles) implemented their pager to remember where you last were, so you don't lose your place. I should explain that more.

Any site that presents lots of items, be they links, pictures, or goods, will break them up into pages. It's easier on them and easier on you (assuming the number of items per page is reasonable). Usually the way it works (roughly speaking) is that they sort by some value, like a price or a name, and then give you, say, the third group of 25.

That's all well and good for result sets that don't change much. Page numbers in a book make sense because the book doesn't change once it's printed. Web sites aren't books. Reddit gets new things constantly. If I'm on page 3 one afternoon, then the next morning when I click to page 4, I won't get what would have been yesterday's page 4. I might get page 3 again, the previous page 2, or a page of results that didn't even exist before.

What Reddit does instead is keep track of the last item on the page. When you click to the next page, instead of saying "grab the 25 links on page 4," it says "grab the 25 links after 't3_6ngfy'." That way you never lose your place. It's better for me, and quite likely better for them, too.

This isn't necessarily the right thing to do for everything that pages. Reddit to my knowledge never deletes links from their results (under normal circumstances). A retailer might do that relatively frequently, in which case this wouldn't work. It would be disastrous to refer to a section of a book by the quote that preceded it. This is not at all a brilliant technique. It's notable because it's different from the default. The Redditors realized that people use their site differently, and adapted accordingly.