If you're new to the world of firearms, then chances are that your greatest exposure to them (until now) came from popular media. Trouble is that the popular media--from fictional depictions to reporting you'll see on the nightly news--gets a lot wrong when it comes to guns. One of the better examples of this is the way that ammunition is discussed. That said, sometimes even "gun people" use the terms incorrectly.
But choosing the wrong words to describe your ammo is a much bigger issue than the minor embarrassment we suffer when we misspeak. Knowing what ammunition nomenclature means is actually important to the safe use and handling of your firearm. That's why our friends at NRAWomen.com (you should really go check out their page!) put this informative video together. Once more into the breach ... er, breech.