Came across this great article on Digital Photography Review
. It asks the question; "What is equivalence and why should I care?" It's an in-depth but easy to follow guide on how sensor size affects depth-of-field, noise, and general low light performance. If you're in the market for a camera or looking to upgrade this is a great read. Also, if you currently own a APS-C camera (smaller sensor, not full frame) this will guide you through important information on what to expect from your camera.
You can check out the article here