Bla bla bla bla...your traffic is shaped even on an "Unshaped" account. It does not make sense for an ISP to not apply shaping or QoS (prioritization) for users.
QoS deals with resource reservation control mechanisms rather than the achieved service quality. Quality of service is the ability to provide different priority to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow. The primary goal of QoS is to provide priority including dedicated bandwidth, controlled jitter and latency (required by some real-time and interactive traffic), and improved loss characteristics. Also important is making sure that providing priority for one or more flows does not make other flows fail.
Shaping is used to create a traffic flow that limits the full bandwidth potential of the flow(s). This is used to prevent overflow problems.
QoS has essentially 3 levels at which it can operate : Best-effort service (no differentiation between flows, aka unshaped), Differentiated service (Some traffic is treated better than the rest), Guaranteed service (absolute reservation of network resources for specific traffic). I can guarantee you that home users will not get a pure "Best-effort" service and will most likely have a type of tailored "Differentiated service". Like it says in the article, "You can’t prioritize one protocol over another without shaping it."
I'll use the Steam example; To prioritize steam traffic you first need to identify and classify it. Steam uses UDP ports 27000 - 27015 and UDP ports 27015 - 27030 ; That's a good starting point for classifying traffic. So you basically give priority to a server with a known IP address (like a dedicated game server) where the communication is happening on the known ports (see above) and you give it a higher priority than say traffic going to port 80/443 (HTTP/HTTPS).
So basically because this traffic gets a higher priority it "moves quicker" whereas your normal web browsing will not be seriously negatively affected especially if (and I'll use a 10 Mbps link as an example) your game traffic consumes a relatively constant 1Mbps, you still have a full 9 available for everything else, and because normal HTTP/HTTPS traffic can wait a ms or two without affecting the end user experience it's not a big deal.
I just wish ISPs will stop lying to ADSL customers by telling them they have an "unshaped" service. The only true unshaped ADSL you will get is a business contract and even then they deprioritize your traffic after office hours.
