There are two things to look for to see if a link TO your website from another website is sending you Pagerank value to boost your position in search engines. Both methods keep search engines from following that link. However, keep in mind that even though a link may not pass Pagerank, no link is a bad one (unless maybe it’s a link from an unscruptulus source), as it can still still drive a live person to your site. Most social media sites use one of these two methods, so they do not provide true links back to your site which improves your ranking in search engines (Links back to your site improve your ranking in search engines – Read more here), BUT there is still value because people can see the link and if they like what they see when they visit, they may elect to manually link to your site themselves or socially bookmark it which shares it with their friends and increases your exposure.

  1. NoFollow – View the source of the website you are on. If you use a
    web browser that allows "View Selection Source", like Firefox, that
    makes this easier. If you use Firefox, highlight the link back to your
    site and right-click and select "View Selection Source." You’ll see
    some HTML code, but you want to look for something that looks like:

    rel="nofollow"

    This tag tells search engines to not follow that link, although people can still click on it.

  2. Redirects – Many sites will use redirects to avoid passing Pagerank
    to your link. You can identify that by turning on the "Status" bar at
    the bottom of your browser if not already on (Look in menu "View –>
    Status Bar") and then hover your mouse over the link on the page
    without clicking on it, look in that bottom status bar to see where the
    link points to. If the site is redirecting, you’ll see something like:

    socialmediasite.com/redirect?url=http%3A%2F%2Fwww%2Eyoursite%2Ecom

    What this effectively does is links to themselves with a parameter
    telling their site to then forward to your site. Again, search engines
    will not see the redirect to you and instead just sees a link to the
    site linking to you.