Building or acquiring backlinks are an important part of the search engine optimization process. Backlinks can be defined as URL that points to a webpage from another webpage in a different domain. Although internal links (within the same domain) can also be considered as backlinks, for the purpose of SEO mostly links from another domain is considered more important. Backlinks are also sometimes referred to as the inward link or inbound link.
There are some important reasons as to why the backlinks are important in the success of your blog or website.
Popularity: The number of backlinks or the quantity of backlinks defines the popularity of the website. The more backlinks that you have from different domains, the popular your website or webpage is perceived to be.
Traffic: Your website receives traffic when people click on links that point to your webpages. The more backlinks you have on other domains, the more traffic you get. This obviously depends on the popularity of the website that has the backlink.
SEO: Search engines use the quality of backlink as a measure in determining the search engine ranking for your webpage in search results. The web pages with good quality backlinks from domains with a good page rank often rank higher in the search results.
As the backlinks are used to compute the relevance and quality of your website, the quality of the backlinks itself matter. As a general rule, the more backlinks you have the better it is but you do have to be careful in that you do not generate predominantly bad quality links. Having a large number of backlinks from a number of bad quality websites such as content farms and paid sites can negatively affect the ranking of your website.
Remember that some percentage of bad links are unavoidable and to be expected and is probably not worth the time and effort to have them removed. The important thing is that it is not an overwhelming percentage of your total links.
Backlinks itself are fluid with many being added and many removed all the time. Sometimes the backlinks expire or are removed or moved by the time you find it. It could still exist in the search engine indexes till those web pages are crawled again. There is no single tool that will show you every single backlink that exists.
There are several tools that you can use in tandem to track down most of these backlinks. Many of them do a good job, but none of them does it completely or you just can’t be sure…
Google Webmaster Tools
This tool provides quite a bit of information about your website including the backlinks in google index. This is probably one of the most comprehensive and the one I use the most. To see the backlinks, in the left hand side menu click on Traffic and then Links to Your Site. It provides you with several options to drill down find the exact page where the backlinks are present.
Another good feature is that they do differentiate between internal links and external links and that makes it easier for SEO.
Open Site Explorer
Another good site from SEOMoz which provides a wealth of information including the backlinks. Unfortunately the good part of it behind a paywall and you have to go pro to access it. I have seen that it does show much less links that the google tools, but does indeed show all the important and good domains. Some of the obscure web domains that showed up on GWT were missing here.
Another method of looking for links is using the google search. You can use the google search operator link: to search for backlinks. This has never given me a complete set of links or anything close to what is shown in the Google Webmaster tools. This is a small sampling of the backlinks.
Another good source of backlink information comes from your own website logs. This is based on the assumption that somebody is actually clicking and visiting the website from the backlinks. While this is true almost all of the time, it does not have to be. From a strictly SEO point of view, the search engines might be indexing these backlinks, though it is not generating much traffic and worse it could be backlink of lesser quality.
In addition to the above mentioned applications, there are several more tools that are available such as Alexa, Majestic SEO, SemRush, and Bing webmaster tools.
Finding and analyzing the backlinks helps you maintain the quality of the website, especially with the search engines. If you feel like your website is generating a large amount of bad backlinks that is hurting your search engine rankings then you can try to remove the bad backlinks, if possible. Google also allows you to mark these as bad links using the Disavow tool.