What is -30,-40,-50 penalty? and how to avoid it when boosting google rank?

Hi guys, as all you know, recently a lot of optimized websites was penalized from the first page to the four page or the five page in Google, as we called the -30,-40,-50 penalty, so could anybody tell me why? for so many sites have been penalized, so i really don't know the exact reason? also, i want to know how to avoid the -30,-40,-50 penalty when boosting google rank, anybody could help me?

Myths. Dont pay attention to all the crap written on DP. Listen less to the hoi polloi and spend the time building instead.