What are the key aspects of Penguin update?

[AliceFowell89]

What are the key aspects of Penguin update?

[JohnVilson]

Penguin is the code name for Google algorithm. Its primary target is to diminish the positioning of that site that are damaging the Google Webmaster rules. These rules are violated by utilizing black hat methods such as cloaking and stuffing.

[Gharkul]

By Google’s estimates,[5] Penguin affects approximately 3.1% of search queries in English, about 3% of queries in languages like German, Chinese, and Arabic, and an even bigger percentage of them in "highly spammed" languages. On May 25, 2012, Google unveiled another Penguin update, called Penguin 1.1. This update, according to Matt Cutts, head of webspam at Google, was supposed to affect less than one-tenth of a percent of English searches.

[RH-Calvin]

Google launched the Penguin Update in April 2012 to better catch sites deemed to be spamming its search results, in particular those doing so by buying links or obtaining them through link networks designed primarily to boost Google rankings.

[TomClarke]

Penguin is th ecode name for Google algorithm. Its main target is to decrease the ranking of that website that are violating the Google Webmaster guidelines. These guidelines are violated by using black hat techniques like cloaking and stuffing.
After penguin update doing SEO has become difficult as like after Google's other update. But this time  it has brought a historic change that is now we need to enhance the content of our site as well as of our backlinks.