Most cows raised in the U.S. are Angus, Hereford and Shorthorn. "Certified Angus Beef" is a marketing term, but an effective one; it applies to most of the beef in U.S. stores [sources: Miller, The Nibble].
A cow's diet has a major role in the flavor of beef. In the U.S., most commercially available beef -- the flavor you're most likely used to -- is corn-fed or grain-fed (usually "grain" denotes corn and soy). This usually means it has been raised on a feedlot.
A growing school of thought opposes grain- and corn-fed beef, on the grounds that these foods are not part of the natural diet of cows. Corn, in particular, can lead to health problems, which is one of the reasons it is so often combined with antibiotics. But the antibiotics themselves are implicated for a whole host of health problems, including new strains of disease-resistant bacteria [source: Time].
The alternative is grass-fed beef. Grass-fed cows graze in pastures -- usually prairies left to grow their native grasses. Grass-fed beef tends to be less marbled than grain-fed beef and it's significantly lower in saturated fat. It has a distinctive flavor, which varies depending on the region and the kind of grass [source: Time]. This is the beef you'll usually encounter at South American steakhouses.
People who are concerned about health -- their own health, as well as the health of the planet -- often seek out beef that is free of growth hormones and antibiotics. By law, no beef may contain antibiotic traces when it is sold to consumers; that, however, doesn't mean it has been raised without drugs [source: Time].
Organic beef must have been raised without hormones or antibiotics. The cow must have been given organic feed [source: Tyree]. But "organic" can mean a lot of different things; sometimes it just means that the cow ate corn that had no pesticides. If you're looking for an environmentally friendly designation, "grass-fed" is actually more meaningful [source: Time].
Many beef producers voluntarily submit their beef to be evaluated by the USDA, which ranks beef according to its maturity and marbling. Prime beef, the top grade, comes from the youngest cows and has the most marbling (that is, the highest fat content). In descending order, the next grades are choice, select and standard.
On the next page, we'll take a look at the different cuts of steak.