What are Unnatural Links?These are links that are not 'earned' but are 'sought and bought' to improve page rank of a particular site. Much like the annoying ads of Bournville that sends the message to earn the rich bar of cocoa rather than buying it, the Penguin update is just an advancement of what Google has been preaching for a long time. 'Say no to web spam' is the Google Mantra, which if taken lightly now, will surely end up in site penalties of the worse kind (read irreversible). Why punish for something now that has been ever existent since time unknown?It is not the timing, but the intensity that counts here. Unnatural links have been a part and parcel of 'cheap and fast' off page link building techniques. The most common practice amongst them was to provide link networks between money keywords (keywords that bring about conversions). Google has been constantly replenishing their algorithm updates to enrich the user experience on their search engine but have even speedily been manipulated by smart black hat SEOs.The punishement has only become severe and more publicly exposed with the Penguin update. The interesting part here is Google has sent about 1 million unnatural link warning messages prior to releasing the Penguin update in a span of a month for the very first time. Why would anyone get unnatural links to their site?While it surely does not justify for sites to equip their backlink profile with spammy and meaningless links on the basis of shortage of time, small businesses really cannot spend a whole lot of time building links naturally to their site with a truckload of other work related issues. On the other hand, big businesses have lots of money to spend on freelance, in-house or professional SEOs to provide quality link building for their sites and acquire consistently incoming quality links. This said, it does not always mean that when you have quality links, these links have come in naturally. So, if you have high PageRank Links of the same page rank with quality content coming into your site during the same period, it can also be considered unnatural. Hence, irrespective of the nature or source of the links it is the behavioral pattern of your link profile that arises suspicion amongst Google bots.What are the links that can be called unnatural?Links that root from:Blog NetworksLink NetworksArticle NetworksPaid Link NetworksNon-niche and irrelevant sitesPaid placements on forums, short text paragraphs and imagesExact anchor text match between niche sitesPoor quality contentSpun/Duplicate ContentTLD's that contain links.html, links.org etc.Low quality, generic and no-editorial control site directoriesAbove 50% money keywordsHidden LinksConsistent PageRank SitesExcessive sitewide links and footer linksMore than one link from a single content to the same page on your websiteMalware attacked or compromised sitesExcessive Guest Blogging Sites (low quality content)Unnatural Recirprocal LinksAs discussed above, it is not just the source of the links that christens it as 'unnatural' but it is the pattern in which the links appear on your link profile. If you have sudden increase in the number of backlinks at a particular time period wherein the link graph was only just a plateau until then, the link behavior is considered suspicious. Similarly, if your domain is a fairly new one and has incredible number of links already, it is seen as a part of artificial links. How to get rid of the Unnatural links?In order to get rid of them, you first need to identify them. There are plenty of link tools available on the web that help you classify your backlink profiles and detect duplicates or bad links. Here are a few:Majestic SEOSEOMoz Open Site ExplorerCognitive SEO AhrefsGoogle Webmaster ToolsYou can first start with cleaning up the sitewide links and footer links from your own site. You can either make these links nofollow or simply remove them. Then comes monitoring linking root domains and making sure to eliminate the duplicates. Remove any dead links or broken links. If you have installed Wordpress Themes, Plugins or Widget on your site, check for any hidden links and have them removed. Here is a guide from Majestic SEO that helps you deal with removal of unnatural links. Here is yet another informative guest blog on SEOMoz.org by Modesto Siotos that gives a deeper insight on detecting and removing unnatural links. Bottom line here is, you are certainly not the only unfortunate one who may or may not have received the unnatural link building warning from Google and experienced a substantial loss of rankings. There has been a recent report of a popular Wordpress Portal that was hit by the Penguin and now is recovering its rankings through some thorough link profiling and clean up. Some Link Building tips Post- Penguin:- First of all, off page link building is not dead. People still do use Google and Google still does rank sites on the basis of its on page and off page SEO. Make sure your SEO company has adopted to the new Penguin update and taken steps to act accordingly.- Invest on some great content writers who can write awesome and informative content for your niche specific topics. Post the content on your blogs and acquire authorship for the same (with your Google+ profiles)- Post a quality content on a high page rank article site and link to your homepage/inner page, whichever is relevant. Spread the same content on the other article sites but link them to the original post on the authority article site you posted initially. This is called article syndication and is no where related to content duplication.- Use real names when commenting on forums or blog posts instead of keywords. The same goes for any social media profiles that you create- Link to long tail keywords or domainname, domainname.com, http://domainname.com or phrases like 'read more', 'click here', I think you get the idea- Stay active on your social network profiles and share useful information. Twitter, Facebook, Pinterest and Google's very own Google+ have prominent impact on improving the way search engines see you.Here are a few more optimization tips for you post the Google Penguin update by Lisa Buyer of SearchEngineWatch.com