As the world turns, so, too, does the housing market -- and right now, the market is slowly but surely turning in favor of buyers. As a result, sellers are likely to see the return of contingencies: those conditions that must be met in order for a contract to be valid.

While a contract can be contingent on almost anything -- Maryland agent Margaret Rome once had a sale dependent on the buyers' parents' approval -- we're largely talking about home inspections, appraisals, financing and the need for the buyer to sell their current residence.

Over the last few years, buyers all but abandoned those safeguards in an effort to beat out competitors. The market was so hot that buyers basically threw all caution to the winds, hoping they weren't paying too much, that they could qualify for a mortgage and that they weren't buying a place with major, costly defects.

Up until a month or two ago, sellers were in the driver's seat, able to practically dictate the terms under which they would accept a buyer's offer. Now, though, buyers are regaining the upper hand. Competition is dwindling. The number of houses for sale is growing. And many sellers are lowering their asking prices.

There's still a way for sellers to maintain control of the process, though. By demanding a "kick-out clause," you have the right to terminate a contingency-laden contract if another buyer comes along and offers a deal without any such strings attached.

Of course, a seller can't simply say, "Hey, I got a better deal. See ya." The first buyer must be given a certain period of time to remove the contingency. But if they don't, the seller can move on to the next. They'll have to return the deposit, but otherwise, the deal is canceled.

The use of kick-out clauses, sometimes known as bump or release clauses, is not universally popular. One agent calls them "an empty bag" that simply mucks up the deal. Another says he dreads them.

Other agents swear by them, though. "As long as there is a contingency," says one advocate, kick-out clauses put sellers in "the negotiating position they dream of."

Says another: "It really wouldn't be wise to stop marketing your home for a 'maybe' contract, and that's exactly what a contingency contract is: a maybe."

But while kick-outs do, indeed, favor sellers, longtime Massachusetts RE/MAX broker Bill Gassett says they also help buyers.

Knowing they can force a buyer's hand makes it more likely that sellers will accept offers with a contingency, Gassett says. And by being able to negotiate price and terms beforehand, buyers will know exactly how much they need to net from selling their current residence.

With a kick-out clause in place, sellers can (and should) continue to show their properties to prospective buyers. And should one come along that doesn't have a place to sell or doesn't need financing, they can give the first buyer so much time -- usually 24 to 72 hours -- to remove the contingency.

If they don't act in time, you can void the contract and move on.

Of course, if the first buyer removes the contingency within the stated time frame, the seller has to continue to closing. Even if another buyer offers more money without other stipulations, a deal is a deal.

The idea is to prevent a buyer from dragging their feet through the process. "Fish or cut bait," says one agent.

All contracts stipulate that the buyer must complete certain tasks within a certain period. Sometimes, though, those deadlines come and go without any discernable progress.

If a deadline is missed, the seller can cancel the sale. But with no other offers in sight, most sellers decide to hang in there, waiting and waiting -- and maybe waiting some more -- until something happens. A kick-out clause lets sellers push buyers to move ahead or drop out.

"With a kick-out clause, the seller has the best of both worlds," says Gassett, who has frequently posted online on the topic. "He has a buyer on the hook, as well as the ability to continue looking for something better."

About the only drawback for sellers is that their second buyers may need a decision right away. Since sellers have to give their first buyers a reasonable period of time to remove their contingencies, the second buyer may not be able to wait. Consequently, sellers could lose a buyer who is willing to make a better offer.

Sellers can invoke a kick-out for any reason, Gassett told me in an email: "Usually it is because the second buyer does not need to sell a house and can close quicker. However, it could be for any number of reasons, including a higher price."

But, he warns, the wording of your kick-out clause can be a little tricky. While many multiple listing services have standard, fill-in-the-blank kick-out clauses, it's always best to work with an agent who has enough experience to ensure the language is correct. And you may want to consult an attorney to be sure the clause says exactly what you want it to say.

"A kick-out clause does increase the complexity of the purchase contract," Gassett says. But it helps you "avoid handing over all the power to the buyer."

Messy kitchens. Concierge services. Coworking spaces. Connections to local businesses.

These and other features are the amenities housing professionals are recommending that builders and developers offer homebuyers going forward.

"What consumers want in a community is shifting, requiring master plan and rental community developers to rethink once-standard amenities and respond to changing needs," says Maegan Sherlock, a research analyst with the John Burns Real Estate Consulting firm.

Take the messy kitchen. Most of us already have one, every time we cook. But that's the point of a "messy kitchen" -- a small annex off the main kitchen that helps keep the main one clean and looking like a showpiece. After all, today's kitchens, with furniture-grade cabinets, granite or quartz countertops and decorative light fixtures, are as much a fashion statement as Jimmy Choo heels.

The messy kitchen houses "those everyday small appliances that see regular use without cluttering those beautiful countertops," explains architect Deryl Patterson of Housing Design Matters in Jacksonville, Florida.

A huge proponent of a second kitchen, Patterson has one in her own house, which she says she uses "all the time." It's where she starts the day making coffee -- but she now wishes it included a sink and a pull-out trash can. Without a sink, Patterson has to walk to the main kitchen's island for water to make her brew. Afterward, it's back to the main kitchen to dump the grounds. Don't ask how many times her filter has broken on the way to the trash can, she says.

Not only is a small second kitchen practical, it's relatively inexpensive: pretty much just cabinets and running water.

Beyond second kitchens, the Burns firm's trend-tracking research suggests three low-cost, high-impact amenities that developers might want to use to attract today's young homebuyers.

First: concierge services. Hotels have long offered this type of assistance: Walk up to the concierge desk, ask where to find a good Italian restaurant or the nearest complete gym, and get an answer on the spot.

But the concierge performs other tasks as well. He or she can arrange events on your behalf, book excursions and transportation, make restaurant reservations and even respond to complaints by taking the appropriate action.

That's exactly what Sherlock sees in the future for housing developments -- at least those large enough to afford it. She says conciergelike services that ease the demands of everyday life will allow homeowners to tend to other priorities.

She also likes the idea of a community-based rental service where folks can check out fishing rods, bicycles, perhaps even lawn mowers. Such an amenity would allow residents to take advantage of seasonal sports like skiing and kayaking without having to purchase and store the equipment.

It's all part of the "sharing economy" today's young buyers have grown up with, Sherlock says. So is the idea for a community-based workplace for those who no longer need to commute to a distant office. And it works for those who don't have enough space in their homes for a dedicated office as well as those who just want to get out of the house.

Sherlock says a coworking space, maybe in the community clubhouse or as a stand-alone building, will meet the needs of the work-at-home set, 40% of whom will otherwise set up their laptops in their kitchens, spare bedrooms or basements at least one day a week. Such space might even go beyond the standard conference room "by providing remote workers the option to rent soundproof rooms or equipment like green screens and lighting," Sherlock suggests.

If providing coworking space isn't in the cards, she likes the idea of partnering with nearby companies that offer such services. "A discounted membership is a great way to support your community," she says.

Linking residents directly to other local services is also a good way of building support. Perks like discounted spa and fitness club memberships, deals at local restaurants and stores, and maybe even happy hour bargains at nearby craft breweries can help people explore and become a part of the community, she says.

Meanwhile, Sara Gutterman of Green Builder Media suggests that builders upgrade their outdoor living amenities. "People are tired of being confined to the indoors, and are looking to design sustainable outdoor living areas to relax, entertain and garden," she says. "In an unpredictable and confusing world, homeowners are finding solace in their porches, yards and gardens."

And finally, builders should consider adding a small space for homeowners' pooches. Patterson says several of her staff members wish they'd had the foresight to build a better place to store their pets' food, toys and bowls. One even wants a doggie shower in the garage where his dog can shake off excessive water.

Patterson's own house has such a dog shower: It's waist-high and features warm water and a high-powered blow dryer. Her husband scoffed at the idea when they built their place a few years ago, but now he loves it. "What used to take an hour per dog now takes 30 minutes for both," she says.

At the same commission rate, real estate agents who sell an $800,000 house receive eight times the compensation of those who sell a $100,000 home. But does it take eight times the effort to sell the more expensive property?

Does it cost agents more to market a higher-priced home? Is it more difficult to find buyers who can afford such a place? Is the sales process more time-consuming? Is there more paperwork involved? More rules and regulations that must be followed?

I ask because a new report from the Consumer Federation of America questions the relationship between home prices and commissions.

Intuitively, you'd think that the commission charged on higher-priced houses would be lower, if only because agents would earn much more money. At 6% in the above example, the agent selling the $800,000 house would earn $48,000, while the one selling the $100,000 house would make just $6,000.

But that's not always the case, according to the CFA, which found "no consistent relationship" between prices and commission rates.

Previous research found a "tendency" for commission rates to slide as home prices increase. But in the CFA's study of the rates charged in 17,800 recent sales, the sellers of more expensive houses in eight cities were charged higher rates, while those in eight other markets paid lower commissions. In 15 other places, rates were either uniform or fairly similar across the price spectrum.

Former Department of Housing and Urban Development official John Weicher once said commission rates are "generally expected" to vary inversely with housing prices, "on the basis that the effort needed to sell a home is not proportional to the price of the house."

But that was in 2006. The market has changed mightily since then. Buyers used to hop in an agent's car to find a home that fit their needs. Now, they do the lion's share of their search online -- so ostensibly, agents do less work.

Some agents argue they must work harder, and at a greater cost, to sell a higher-priced property. Expensive places tend to be larger, requiring more inspections, property clarifications and "making sure the buyer and seller are happy," Northern Virginia broker John Marcario told the CFA.

But others disagree. "I don't think the cost to sell a home (here) in Massachusetts for $100,000 vs. $4 million is any different," said 40-year realty veteran Tom Wemett of Homebuyer Advisors. "What is different is the profit."

"Generally speaking, an $800,000 house is no more work than a $300,000 house," added Derek Eisenberg of the Continental Real Estate Group in New Jersey.

There are market conditions to consider, of course. In extremely high-priced places like California, where $800,000 houses "sell like popcorn," it's likely more difficult to sell a $100,000 house, consultant Marilyn Wilson of the WAV Group told me.

That may be so. The CFA found that in Bakersfield, California, commissions on two-thirds of the houses that sold at $450,000 or above were higher than on those that sold for $300,000 or less. Yet in San Diego, commission rates hardly varied, no matter the price.

Another anomaly might be whether it's a buyer's or seller's market. Danetha Doe, an economist with Clever Real Estate, told the CFA that when the market favors buyers, "it takes more effort" to sell a pricier place.

Another consideration is the type of property. According to Eisenberg, more work is involved in the sale of condominiums, houses governed by homeowners' associations and houses where the owner is in financial distress. Other factors are the property's condition and location.

All that said, I threw the question out to some agents with whom I am in regular contact. Here's a sample of their responses:

-- "The amount of work required to sell a home is not distinguished by price," said Robert Goldman of Michael Saunders & Co. in Venice, Florida, but rather by "five factors: condition, location, staging, marketing and price."

-- Chris Carter of Waterfront Realty in Naples, Florida, says he expends the same amount of effort, no matter the price. But he points out that when their cut is larger, some agents are likely to spend more on marketing materials: better photos, maybe including drone shots; full-color printed postcards; and single-property websites. Then again, when the market is hot enough, agents may do little more than list the house and wait for offers.

-- Lisa Abrams of Berkshire Hathaway, who is licensed in Florida and in the D.C. area, says that her effort doesn't change with the price point, but that she does find it more difficult to sell cheaper houses. "Typically," she told me, "buyers in the lower price points tend to have financing issues and down payment issues."

Carter said the same: Buyers of expensive properties tend to be "more sophisticated and experienced" and "don't require as much hand-holding."

-- Charles Hunt of the New York-based Hunt Real Estate Group agreed, adding, "Selling a less expensive home can have more steps due to financing and inspection contingencies that may not exist on a more expensive property."

Finally, a word on commissions: Both sellers and buyers need to pay better attention to what each side is paying, as well as how and why. Don't be so preoccupied with the selling price and the timing of closing that you don't ask about commissions.

Discuss the rate with your agent before signing anything. Ask whether they'd be open to a lower fee or to sharing a decrease with the other side's agent. And in the 41 states that permit rebates, ask whether your agent is willing to give back part of the commission at closing.