The number of sites linking in that Alexa reports is the number of websites in Alexa’s crawl of the web that link to a given website.

Here are a few explanations for cases where you know of links pointing to your site that Alexa does not list:

  1. We count the number of sites linking in, and not the number of pages. (Only one link from a given site is counted.)
  2. We update the number of sites linking in only once per week for all sites.  (Although the links-in count for sites with Certified Site Metrics are updated daily.)
  3. We don’t count links from link farms or other similar search engine placement mechanisms, such as links that are obviously from link exchanges.
  4. We don’t count links that appear in search results on a major search engine (such as Google, Bing, etc.). We do count top-level links to search engines.
  5. Alexa’s crawl of the web is focussed on pages that have measurable traffic.  If we can’t measure any traffic to a given web page, then it is less likely to be crawled and the links on that page will not be counted.

The Alexa traffic rank is in no way related to Sites Linking In.

Note: We do not show links from adult sites in the Sites Linking In list, but they are included in the Sites Linking In count.