Snowshoes spread your weight over a larger area keeping you from sinking in soft snow.
Snowshoes typically come in 2 or 3 sizes 8" x 25" (120lbs - 180lbs.), 9" x 30" (160lbs - 220lbs) and 10" x 36" (200 lbs and over) and are $175 - $250.

They are also good for soft snow with a hard crust where postholing (breaking thru the crust) can make hiking miserable. You have to shorten your stride to pull your foot back up thru the hole and avoid bruised ankles where they hit the crust as you stride forward.

In powder snow deeper than your knees even 30" snowshoes will not keep you from sinking. It is best to use skis or let someone else break trail. ( Forums)

Rotating (or floating) bindings pivot at the point where they attach to the decking--under the balls of your feet. This movement allows you to walk naturally and to climb hills.

The amount that bindings pivot varies among models. Some bindings are attached with metal rods and pivot 90° or more. This causes the ends of the snowshoes, called tails, to fall away as you step, shedding snow and reducing leg fatigue.

Heel lifts: Also known as climbing bars or, on MSR models, Televators, these wire bails can be flipped up under your heels to relieve calf strain on steep uphill sections and save energy on long ascents. This feature gives the feeling of walking up steps and prevents exaggerated calf and Achilles strain.
Source: Snowshoes: How to Choose |

Sometimes you only need a little larger footprint to keep from postholing.
The MSR Evo 22 and and MSR Denali Classic
are molded plastic snowshoes 22" long - $100- $140
You can add a tail extension to make them larger.
They are best for crusty hard snow. Wet heavy snow can get stuck between the ribs on the bottom making them very heavy.

Running snowshoes typically have lighter-weight construction and bindings than your average snowshoe. The bindings are designed with running shoes vs. boots in mind. There is typically an extra cleat under the toe for additional traction while running on packed trails.

"How to put on a Snowshoe" by SIA Nordic on Vimeo.

Some snowshoes don't have a left/right marking.
The tightning strap buckles should be on the outside.

The outside (left) and inside (right) of the right snowshoe and binding.

First-Timer's Guide to Snowshoeing | Snowshoe Magazine
Snowshoes: How to Choose |
Selecting the Right Snowshoes :
Snowshoe Advice @ BackpackingLight
  Atlas 10 Series All Mountain Snowshoe REVIEW @ Backpacking Light
  Tubbs Catalyst Snowshoe REVIEW @ Backpacking Light

last updated 14 Feb 2015