Informer's World

Most of the webmasters do not know about Search Engines penalty, but most of the major search engines like Google and Yahoo penalize sites to clean up their results delivery. There are several types of Search Engine Penalties and I already mentioned some of them.
So, when you notice sudden drop in referral traffics from Search engines like Google, you should do some immediate research to know if anything went wrong as Google do not provide direct information regarding penalties.

1. Lost Rankings
   
   You should always keep track of your rankings in Google for keywords. The most reliable tool for this is Google Webmaster Tools. Check them to see if everything is all right.
2. Keep Track of your Backlinks
   
   This also helps to determine if you hit by a penalty. Searching for link:domain in Google shows the number of indexed quality backlinks for your site. You can also check the actual number of indexed backlinks by Google in Google Webmaster Tools. If the numbers are going down, there’s a possible penalty.
3. Domain Name Search
   
   Search Google with your domain name without the extension (i.e, search for w7b if your site is w7b.org). If your site isn’t a new one and other sites are outranking you or your site is ranking at fifties, there’s a positive penalty.
4. Keep Track of your indexed pages
   
   Always keep track of your indexed pages. Searching for site:domain operator in Google shows the number of indexed pages. If you see its going down, there must be something wrong with your site. If you use a sitemap and your site was down for several days, the number of indexed pages may also go down.
5. Unsafe Browsing
   
   Check if Google has blacklisted your site as unsafe for browsing. Type the URL in address bar replacing the domain.com with your domain. http://www.google.com/safebrowsing/diagnostic?site=domain.com. It also shows if any of the sites hosted in the same network ever blacklisted as unsafe from browsing. Do a security scan form cPanel and remove all the suspected files. Then place a review request from Google Webmaster Tools.
6. Injection
   
   Check your site’s source codes for any injected links to spam sites. Remove them if necessary. You should also check your SQL Database for the same if your sites uses one.
7. Article Title Search
   
   Search in Google for a unique article title from your site in Google to check if that page is ranking number one. If other sites are outranking you for that same long tail keyword, there may be a possible penalty.
8. Dropped PR
   
   This is what I am not 100% sure. There’s a say that if the toolbar shows a gray PR or PR not available for a site which had some PR before might got a penalty.

Those are the basic things to make sure if a site received penalty or not. please let us know if there’s any other ways.