GOOGLE PANDA

Read this quote from Google's official blog post when Panda was launched.

This update is designed to reduce rankings for low-quality sites-sites which are low-value add for users, copy content from other websites or sites that are just not very useful. At the same time, it will provide better rankings for high-quality sites-sites with original content and information such as research, in-depth reports, thoughtful analysis and so on.

Basically the panda update was an update not necessarily targeted towards spam, but website with low quality content that offer less or no value to its visitors. These website are also referred to as content farms.

Panda was majorly focused on site quality which involves the number of pages a site has and the amount of content on the pages.

GOOGLE PENGUIN

The Google Penguin Update launched on April 24th. According to the Google blog, Penguin is an "important algorithm change targeted at webspam. The change will decrease rankings for sites that we believe are violating Google's existing quality guidelines." Google mentions that typical black hat SEO tactics like keyword stuffing would get a site in trouble, but less obvious tactics (link incorporating irrelevant outgoing links into a page of content) would also ca