What are backlinks and how do I use them?

Backlinks enable you to keep track of other pages on the web that link to your posts. For instance, suppose Alice writes a blog entry that Bob finds interesting. Bob then goes to his own blog and writes a post of his own about it, linking back to Alice's original post. Now Alice's post will automatically show that Bob has linked to it and it will provide a short snippet of his text and a link to his post. What it all works out to is a way of expanding the comment feature such that related discussions on other sites can be included along with the regular comments on a post.
The backlinks setting can be found under the Settings | Comments tab and consists of a single, simple option to turn it on or off:
Our default templates are already set up with the necessary code for backlinks. However, if you have a custom template, or one of our templates from before this feature was launched, you will need to add the code yourself. Instructions for that are here.
Once everything is set up and you have republished your blog, you will see the number of backlinks listed for each post, along with the number of comments:
If you click that link you will be taken to the post page, where the backlinks are all listed beneath the comments. Clicking the triangles next to each link will display a snippet of text from the page linking to you, as well as some author and date information.
If you want to turn off backlinks for individual posts, you can do so. The process is the same as that for turning off comments. Just edit the post in question and change the options that appear below the posting form:
Notes:

• For the curious, this feature is based on the link: operator of Blog Search. So sites linking to your blog will need to be indexed by Blog Search and there may be a slight delay before the backlinks appear on your blog.
• The comment notification email setting does not apply to backlinks, so you will not be notified of new links when they appear. This is because these links are looked up on-the-fly each time you view an individual post.
• In lieu of comment notification, you can use Blog Search with a query such aslink:your-blog-here.blogspot.com and then subscribe to the results. That will have a similar effect.