If you don't know what a "backlink" is, it is simply a link on another website that points to your website. A backlink is basically a vote for one website to another. The higher our rank in search engines, the more backlinks we have pointing to our sites. Higher rank means more traffic and sales. link indexing
This is the quick version. Many people don't realize that if a backlink is placed on a page of a website, but it is not in Google’s index, the backlink will not work and your rankings will suffer. Why? Google won't know anything about a page if it doesn't have a backlink to that page. We need to ensure that all pages that contain a backlink to our site are indexed by Google. This can be done in many ways. We just need to help Google locate these pages and add our backlinks into their links database.
Many people wonder why this is necessary. It is easy to answer. The answer is simple. Although search engines are equipped with many servers that can perform different tasks, they still have to process billions of pages. Even with a sitemap, it's easy for pages to be buried if a website is constantly adding new pages. This makes it difficult for search engines to find them. re-index
How do we index these pages? The concept is simple, even though the timeframes can vary. As search engine bots are likely to frequent these sites frequently, we use a variety of sites including popular bookmarking sites and forums. We simply link to our "backlink pages". You would bookmark the URLs on bookmarking sites, and for forums you would add the link to your signature. This would populate hundreds of indexed threads with the link. These methods can be used to index your backlinks in minutes.