Google frowns at any form of paid link or unnatural linking, if you have been doing this it is better you stop before you get caught.
“Just because it is fine with Google doesn’t mean it is legal”.
Copyright violation is frowned upon by Google, hence you hear Google promoting the use of original content. Copyright violation is a surefire way of getting your pages de-indexed from Google
Hiding keywords or phrases with the background color technique is just so wrong and Google already knows about this technique. This could easily translate to your pages disappearing from Google search.
Linking To Spammy or malicious pages
Google, Bing and every search engine hates spam. Always check pages you are linking to, even if it is a guest post, check the links to make sure you are not sending your readers to malicious pages.
Once you have been infected with malware or your site is linking to such a page, you are on a ticking clock.
These are just some of the ways you could get banned, blacklisted, de-indexed by Google. Always make sure you read and understand Google’s terms and keep yourself updated on their algorithm changes. Penguin, panda, hummingbird these are all algorithm changes your should read about as they could be responsible for your rapid drop in traffic.
To Check is Your Website is Blocked or not by Google Visit the the post in given link below,
AdSense Banned Check is a powerful set of tools that verifies if your website and/or domain has been banned by either the Google Search Engine or Google AdSense. Keep in mind though, that this will not indicate if your personal AdSense account has, or has not been, banned from Google. It will let you know if your Website has been banned by Adsense. Website/domain verification is especially usefull when you plan on:
Checking if your site has been banned by AdSense.
Opening a new AdSense account.
Transfering your domain to a new name.
Selling your domain to someone new.
Researching if an existing domain has been banned by AdSense.
Checking to see if your competition has been banned.
Check to see if your website and/or domain is banned by both the Google Search Engine, and by Google AdSense, by entering your website name in the given website. Be sure to check your site with 'www' in front, and without to see if either have been banned.
Also, don't forget to check out the other services this site has to offer.
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