Digging in to Dim Weight

My shipment weighs 300 lbs., but my bill shows it was "recalculated" to 570 lbs. What is dim weight and why was I charged more?
Recently we posted a blog, The Dim Weight Dilemma that addressed this question and provided an in-depth explanation of how a shipment's weight can change, even when the scale doesn't.
But you're back for more so I'd like to break it down and dig into dim weight a little deeper. Whether you are looking for an easier way to plan your trade show shipping or general freight shipping, working on event planning logistics or preparing for the Jeopardy! category "All Things Shipping", this information should prove useful.
Ready to wow your friends and family and be the freight logistics expert you have always dreamed of being???
Here are our top three frequently answered questions:
1 - What it is
Wikipedia defines dimensional weight, as "a pricing technique for commercial freight transport (including courier and postal services), which uses an estimated weight calculated from the length, width and height of a package."
It's a method the shipping and trucking industry uses to determine the true cost of moving a shipment based on the amount of space it takes up.
2 - What it isn't
It's not a "pricing scheme" created by 3PL companies to take more money out of your budget
It's not a complicated, convoluted mathematical formula
3 - What's the Cost
So will "dimming" your freight cost you more?