You can now target sponsored links to particular communities, and rerun them without losing the comments

We've been very happy with the way that our sponsored link system has been used. Advertisers seem to have been pretty happy as well. Like all things that ain't broke, we decided, 'Let's fix it!'"

For the visual among you, TheOatmeal was nice enough to make us a walkthrough of the new system.

For those of you who want to get down to business, here's the link.

In this major revision, we've added the ability to target specific reddits (and the subscribers thereof) as well as the ability to extend links. We've been running in a private beta for a few weeks to get the bugs worked out, so you may have already started seeing examples of the new ads popping up. If you didn't, great: it means we've succeeded in making this unobtrusive. Targeted sponsored links will appear at the top of the hot listing for the targeted reddit as well as at the top of the hot page only to users who subscribe to that reddit (gory details below). One of the key features of sponsored links is the ability for advertisers to actually interact with the community they are helping to support. In the previous system, once an ad had run its course, it was gone, never to be seen again. Sometimes, this was for the best (you know who you are). Other times it meant that a really productive and interesting comment thread on an ad was cut short. To fix this, we've created the notion of "campaigns" around links.

Once a sponsored link is approved, it can be rerun at any time (as soon as tomorrow rather than our current 48 hour waiting period). This means a popular ad can be extended and, since these campaigns can be targeted or untargeted, moved around to other potential target reddits to extend the conversation.

Here's the gory details on how the new algorithm works. Like our original version, the new version is built around the notion of everyone paying the same CPM. For any given day, we take the pool of all bids for that day, treat them as the cost for "selling out" reddit's advertisements for that day, and allocate each advertiser a slice of the pie commensurate with their contribution. To include targeting we added two refinements to this:

• Targeted links will compete with untargeted sponsored links on the front page, but only when the current user is a subscriber to that reddit. In this case, the bid will be weighted by the traffic of the targeted reddit relative to an average front page reddit. (In this way, targeting to /r/reddit.com or /r/politics is just like running untargeted, but targeting /r/music would get a 2-4X boost).
  


• On the hot listing for each reddit, we compute a separate pool of just links that are targeted to that reddit. If there is no pool, there are no ads. If there are, we divvy up pageviews by contribution, and (unlike on the front page) render one at the top on every page load (rather than intermingling it with new links).
  

We're trying to keep these links as unobtrusive as possible. If you are logged in and you don't like an ad, vote it down and it won't show up again to you. As before, if you like an ad, vote it up (and it still won't show up again).

We'd also like to thank our beta testers who were brave enough to risk their time and money on a potentially unstable ad platform for the last few weeks while we got the bugs out.

tldr: oh look! here's a web comic!

Edit: Cool! We're in TechCrunch!