What Exactly Is Sterling Silver?

There is a common misconception about sterling silver that I'd like to address, and also discuss precious metal vs base metal in jewelry making.

I've started making jewelry in sterling instead of base metal. I like the look of burnished copper and brass, but many women prefer precious metal. And with the amount of time it takes me to make one piece of jewelry, it makes more sense to use sterling silver. My designs involve a lot of wire work, and putting 2 or 3 hours labor into a piece makes it deserve a higher price than I feel comfortable with charging for a jewelry piece made of base metal.
Here's an interesting fact about sterling silver. It isn't pure silver. Pure silver is called 'fine silver', and isn't used very often, because of its' softness. Sterling is an alloy of silver, and is sometimes marked .925 This signifies that it's 92.5 % silver, and the rest an alloy, usually copper.
Another type of sterling, is Argentium silver, which is never less than 93% silver, and has a bit of germanium in addition to the copper, which acts to retard tarnishing. Some of the silver wire I use is Argentium sterling, and I can see the difference in the length of time before it begins to tarnish.