Whey protein

What exactly is whey protein? Is it that beneficial? Does one manufacturer really differ from another? How much of it can the body utilize/absorb? Is casein bad for you? What amino acids should be in high quantity in the whey protein you buy?

Google search: whey protein composition or amino acid composition

http://en.wikipedia.org/wiki/Whey_protein

http://www.wheyoflife.org/faq.cfm#1

http://classes.ansci.illinois.edu/ansc438/Milkcompsynth/milkcomp_protein.html

http://www.huffingtonpost.com/kathy-freston/a-cure-for-cancer-eating_b_298282.html

Milk proteins contain whey protein and casein. Whey protein is mainly composed of beta-lactoglobulin, alpha-lactalbumin, and bovine serum albumin. The amino acid sequence can be found here. http://www.expasy.ch/