One critical component of search engine optimization (SEO) is building links to your website. These links can be called “inbound links” or “backlinks”. Although one of the most tedious component of SEO, link building can be the determining factor in having your website position on page one versus page two. It can be what enables you to be differentiated from your competition, possibly even moving your site above theirs in the search results.
To build quality links to your website and to utilize your time most effectively while doing so, it is important to note that not all links to your website are perceived as being equal to the search engines. The SEO value or “link juice” that is passed to your site from a link can be determined by many factors. Below are a few things to look for when establishing a link building program:
Are the links nofollow?
A link that is nofollow is essentially telling the search engines: “Don’t follow this specific link.” This is an HTML attribute that enables webmasters to tell the search engines to not transfer “link juice” (PageRank or anchor text) from these links. The search engine will still technically follow the link.
There a few ways to identify if links are “nofollow”. First, you can take a look at the page’s source code to see if the nofollow tag (rel=”nofollow”) exists. Another easy way to determine if a link is nofollow is to install a tool such as the SEO for Firefox plugin. With this, the nofollow links will be highlighted in red.
Does the link come from a page that is restricted in the robots.txt file?
A robots.txt file is uploaded to the root of a website’s domain to tell the search engines to not crawl specific pages on the site. Therefore, as the search engine will not crawl these pages, links from them will not pass any “link juice” or SEO value to the destination page.
Redirects can also keep that valuable SEO “link juice” from being transferred through a link. 301 redirects are the most SEO friendly way to tell the search engines that a change of address has occurred for a particular page. If the page that contains the link is 302 redirected (temporary redirect), the links from this page will not be followed. There are a few tools out there that can help you to determine how a web page is redirecting and this is one that I use frequently: Rex Swain HTTP Viewer.
There are other things that can prevent “link juice” to be passed from another site to yours, but hopefully these will help to identify the most obvious ones.