Panda update:-
Panda update is an algorithm designed to reduce rankings for low-quality sites:
- sites that copy content from other websites or
- sites that are just not very useful or
- sites with poor user experience
Here’s about it in detail:
http://www.keywordcountry.com/blog/g...-panda-update/
Penguin update:-
Penguin update is the latest Google update affecting sites with a severe lack of natural links. It is a fight against all existing forms of webspam including link spamming/ trading, keyword stuffing (and other forms of over optimization), aggressive overuse of exact match anchor text, submitting to low quality article/ blog directories etc. Here’s about it in detail:
http://www.keywordcountry.com/blog/g...urvival-guide/