How Back-Link Profiles Have Changed Since Google Penguin
Google’s Penguin update was designed to clear out the websites with over-optimized back-link profiles.
A back-link profile is an overview of all your inbound links. For 8 years, up until the birth of the Penguin algorithm, the way to get your website to the top of Google was to include your keywords in all the key indicators on your page, and then build lots of links from the best Google PR pages you could find, using the exact match keyword as your anchor text.
This works very well. Too well in fact, so Google set about devising a better algorithm that would measure websites for nature linking behavior, rather than rewarding artificially promoted sites.
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