Some time ago Xbox Live went forth and created an imaginary number called the Gamer Score that people compete over. Well, with the Steam Trading Card access now those obsessive compulsive gamers can find a new way to flaunt their "success"... by collecting cards!
Every "steam badge" you get is worth a certain mount of Experience points that determine your "STEAM LEVEL". At the time of posting this, your steam level does not affect (NOR is affected by) achievements. Just badges.
The method badges are earned are usually steam based, community interaction and steam sales being the main ones. However a new way to earn badges is currently in beta and that is known as the Steam Trading Cards. In order to earn a game's badge you have to collect the entire set.
Now, here's where it gets tricky! As the beta stands right now, you can only earn so many cards by playing, and which cards you get is random. Don't Starve for example lets you earn a random THREE out of the total FIVE cards... and then NEVER EARN ANY MORE -- EVER!
How do you complete the set? Simple! Interact with other players and trade them for it!
Okay, so for some people that's not simple at all, darn near impossible. But it's okay, you can use the steam market to buy the cards from other players for real life money.
So, what happens if you are unwilling to trade any of your cards AND aren't willing to shell out cash? At this point in time, you will likely be unable to complete the sets.
Now for Free to Play games such as Team Fortress 2 there is another modus operandi. Just playing the game on a 'free' account will give you no cards. Once you get a 'premium account' by way of either buying a product on the MANN-CO store, or having owned the game prior to it going free to play you will gain 'premium status' and gain eligibility for 5 card drops with on additional drop per $9 spent from that point onward.
As far as free-to-play games go, I can only surmise that this system is designed to encourage purchases in free to play games, thereby supporting their developers (in this case Valve). I personally think it is a brilliant idea and should be applied to as many games as possible. That said, I would really like to see an alternate way to earn more cards without taking the "TRADING" out of trading cards.
The best feature of all this is that it is 100% optional, and other than your "Steam Level" appearing when people mouse-over your icon, there are NO in-game advantages or disadvantages to being a card collector or not. I am sincerely looking forward to seeing how this system evolves as time progresses.