You arrive at the airport earlier than the recommended two hours, just to be safe, and sort through the check-in lines until you can finally speak to someone at the counter. This politely smiling person reports to you that, unfortunately, the flight has been overbooked and would you like to volunteer to give up your seat? And you say, "Um, what?" What follows, if you've never experienced this before, will be a heated argument over your well-planned and confirmed reservation and the legality of this airline practice called "overbooking." To better prepare for the possibility of experiencing this crisis, let's start with the basics.

Overbooking is the airline's way of assuring that no seats are wasted (and, more importantly for them, that no money is lost on empty seats) on a flight. The airline sells more seats than are available on the plane to compensate for the near-certainty that one or more people will cancel or fail to show up. Most of the time, this works according to plan. Sometimes, however, not enough people cancel and, suddenly, there are too many people and not enough seats. This is when the gate agents start asking for volunteers to be "bumped." To volunteer means to give up your seat.

Numbers from the first 3 months of 2015 show that Delta bumped the most passengers (over 40,000), with Southwest and United bumping 23,000 and 19,000, respectively. That's 15 out of every 10,000 Delta passengers, which is well below 1% but still seems like a large number of people losing reserved and confirmed seats. Unfortunately, this is the reality of airline companies' money-saving policies.

So you're bumped, and now you don't have a flight. Why would anyone do that? From January to March 2015, 143,000 people were denied boarding. Airlines try to compensate for this awful surprise by offering bonuses in the form of food or drink vouchers, upgrades to first class, points or coupons, access to special lounges and even money. In fact, some travelers have developed strategies to increase their chances of being bumped so that they receive rewards.

Arriving at the gate early and carrying on luggage instead of checking bags increase your chances of being asked to volunteer. Compensation gets better as take-off time approaches, so you can use that to your advantage and negotiate better rewards. If you're going to sacrifice your seat, however, some suggest waiting to be "involuntarily denied boarding."

The compensation for this is automatically better than anything you can negotiate as a volunteer. The DoT requires that if the airline doesn't arrange substitute travel, you must receive "400% of your one-way fare, $1350 maximum." That's probably twice what you'll get by volunteering. It's also in addition to a full ticket refund.

If you're willing to have your seat taken away, provided that the airline doesn't find enough volunteers, then you'll want to get written confirmation that you've been involuntarily bumped. You'll also fill out an airline compensation claim. Keep receipts from food, drink, transport and accommodation purchases so that you'll be accurately reimbursed for those expenses. You can also use a website such as RefundMe to file a claim, though they'll charge a commission fee.

If you've been involuntarily bumped and are seriously inconvenienced, the important thing is to work with the people and services at the airport to make accommodation and travel plans as easily as possible. You can worry about filing the claim and all of your complaints later—the claim period for airlines is three years. Whether you're stuck for a few hours or overnight, and whether it's two states south or across the Atlantic, take the surprise bonus time to breathe deeply, realize that you're in a situation that can't be changed, accept the bonus time you've been given and enjoy the services of the airport or the surrounding area. Take the opportunity for a last-minute excursion, a visit to a local bar or simply a stroll around a new environment. You never know what a surprise opportunity will present.