If Google's Penguin update earlier this year proved anything, it was that search giant cares about the quality of the backlinks pointing at a website. Furthermore, it has the tools necessary to detect and penalize low-value links that have been created to manipulate page rankings.

So if you've seen a decline in your site's performance since the Penguin update, or if you'd just like to protect your site from future problems, consider these techniques to remove bad links and avoid penalties:

1. Identify low value links within your backlink profile.
The search engines prefer to look at backlinks as "editorial votes" -- that is, they believe an inbound link pointing at your website represents a vote of confidence from the referring site. In a perfect world, the site with the most links from the best websites would be ranked at the top of the search results.

But of course, we don't live in that perfect world. Today, unscrupulous webmasters have made it their goal to "hack" this valuation system, resulting in linking strategies that artificially inflate a site's backlink profile. Although the search engines haven't always been able to effectively detect and penalize this manipulation, they're getting better at it every day. And the Penguin change has shown conclusively that they're ready to penalize webmasters whose sites use such techniques.

With this in mind, the first step in protecting your site from search engine penalties is to identify any links that could be perceived as low value or intentionally manipulative. You'll need to first get a copy of all the links pointing at your website, using tools such as Majestic SEO ($49.99+/month) or the Open Site Explorer ($99/month, following a free trial).

Export your links to a spreadsheet or use your chosen program's internal research tools to identify links that meet any of the following criteria:

  • Is hosted on a website that uses a different language than your own
  • Is hosted on an adult-oriented website
  • Is hosted on a site that offers no value to readers; such sites are often built for the sole purpose of granting links to other websites
  • Is hosted on sites that have been hacked or infected with malware
  • Uses keyword-optimized anchor text (for example, a link that reads "cheap car insurance quote" rather than "click here")

Search engines won't necessarily penalize you for having some keyword-rich anchor text, but when anchor texts collectively aren't diverse enough, it appears unnatural and can raise red flags, particularly if they're on low-quality sites.

2. Determine which links should be removed.
Although all of the above criteria should be cause for concern, seeing a link that falls in the "low quality" category isn't necessarily a bad thing. If the link is no longer active or has been tagged with the appropriate "no-follow" tags to instruct the search engines to ignore it, you don't need to worry about removing the backlink.

To determine whether or not a link should be removed, take the following steps:

• Click each link within your spreadsheet. If it is no longer active and redirects you to a 404 page, you don't need to pursue removal.
• If you are able to reach an active web page that's hosting your link, right click on the page to open its source code. If you see the tag <META NAME="ROBOTS" CONTENT="NOINDEX, NOFOLLOW"> in the <head> section of the page's code, you do not need to pursue removal. The webmaster has instructed the search engines not to scan this page for links.
• If you do not see this code in the header, navigate through the source code to find the link pointing at your website. If the tag <REL="NOFOLLOW"> has been appended to your link, you do not need to remove it.

In nearly all other cases, the link you're researching is active and is being counted by the search engines. Because these signals may indicate a manipulative or low value backlink, you'll want to move to step 3 for details on how to remove these bad links.

3. Contact website owners to request a change.
Begin by finding the contact information for the website's owner. In most cases, this information is on the "About" or "Contact" page. You also search online for a free "DNS Lookup" tool, which will allow you to enter the URL in question in order to find the webmaster's email address that's on file with the site's domain registrar. 

When you contact the webmaster, request:

  • The deletion of the link
  • A change of anchor text to something that's not keyword-optimized
  • The addition of the appropriate no-follow tags so that your links are no longer active

Unfortunately, not all webmasters will respond to your requests. But by documenting the efforts you've made to clean up your backlink profile, you'll be well positioned to respond to any future penalties using the search engines' reconsideration request procedures.

Alternatively, if you used a link building service to create high volume backlinks in the past, try contacting the service directly to see if it will delete or change your links for you.