Did you know why Google released the first algorithm which was Google Panda in 2011?
The reason was google use machine learning algorithms, so they know good sites and bad sites.
Panda was released google said after 2011 google only focus on user experience, not a good sites and bad sites.
Firstly Panda version discovered on page SEO of every each site mostly sites were just ranked with 1000000 social bookmarking, 100000 directory submission, 10000 article submissions etc, they didn't focus on on-page SEO so most sites were penalized because of panda update. now today is broad core algorithm time, still google just announced improve quality of your sites, not any important thing,
"Follow me @alizafar for more information*
