Ever seen something so awful that you wanted to share both the link and your outrage? Most of us have (CNN's recent front page spread on Miley Cyrus and "twerking" comes to mind).
Here's the problem: when you link to a site, you're adding pageviews to their traffic count. Traffic count is a primary factor in a search engine algorithm. By linking to something, and adding to their pageviews, you're adding to that site's seach engine status. The income of most sites is directly related to those very metrics which you're boosting by sharing that link. Essentially, you're paying them for that awful post. Not exactly the outcome you had in mind, is it?
This is the problem that DoNotLink addresses. When you use the service, by entering a link on the homepage, DoNotLink will create another link, which will take those who click on it to the original url, but which will also block crawler bots from crawling the site, thereby not adding to its traffic.
Basically, you're linking to something without helping it get bumped in search results.
To use the Cyrus example, I was a bit taken aback when I realized that I saw that CNN post. I wanted to share it, to bring attention to the fact that CNN had, at least on that day, left its journalistic integrity at home. I couldn't / wouldn't link to it, though, so instead I linked to an Onion post which, in true Onion style, satirized the whole thing.
With DoNotLink, I could've shared the original link without burdening my conscience. In their own words:
"...you can post it on forums, message boards, reddit and other public places without giving shady websites any undue credibility."
When you use the service, you'll get back three links: one direct link, one HTML link to embed it on any website, and a BBCode, which is a markup code used in many messaging boards.
DoNotLink's website links to a great example of just the kind of thing they're trying to prevent- an article explaining how many users complaining about a fraudulent website actually made that website show up number one in Google search results for the relevant keyword.
We love tools like this: solving a widespread problem with a simple, straightforward, and ubiquitous tool. Consider this the Sssimpli seal of approval.