Millennials — the generation born in the 1980s and '90s — have often been "criticized as spoiled, impatient, and most of all, entitled," says Leslie Kwoh at The Wall Street Journal. Instead of being hammered into shape once they graduate from college and enter the workforce, these young whippersnappers are making demands of their new bosses — and, surprisingly enough, "companies are jumping through hoops to accommodate" them, says Kwoh. Here, a guide to how millennials, also known as Generation Y, are transforming the workplace:

What kind of changes do they want?
Millennials want more flexible work hours, feeling that it's pointless to adhere to a rigid 9-to-5 schedule if they can still get their work done without being tethered to a desk. They want companies to take advantage of technology and embrace Skype and other forms of telecommuting. They want the freedom to use social media; some have even quit jobs that bar Facebook at the office. They want big responsibilities as soon as they arrive, and they want to be promoted quickly. Above all, they expect their jobs to be fulfilling: According to a recent MTV survey, 90 percent of millennials believe they deserve their "dream job."

Why are they so demanding?
"The current corporate culture simply doesn't make sense to much of middle-class Gen Y," says Emily Matchar at The Washington Post. This "pampered, over-praised, relentlessly self-confident generation" is accustomed to having "control and choices," and that extends to work. According to the MTV survey, 81 percent of millennials said they should be able to set their own hours, 70 percent said they need "me time" on the job, and 79 percent think they should be allowed to wear jeans at the office. In addition, 76 percent believe "my boss could learn a lot from me," and 65 percent say they could mentor older workers in technological matters.

And companies are falling in line?
They're starting to. Some companies have begun introducing an "unlimited paid vacation policy" at the demand of younger workers, says Kwoh. Others have adopted a "results-only work environment," or ROWE, "a system in which employees are evaluated on their productivity, not the hours they keep," says Matchar. "In a ROWE office, the whole team can take off for a 4 p.m. Spider-Man showing if they've gotten enough done that day." Other companies have experimented with a guaranteed promotion system, or pushing back the time when the office opens.

Why are companies catering to millennials?
Well, they're literally the future. Millennials are expected to compose "40 percent of the U.S. workforce by 2020," says Kwoh. Millennials are already gravitating toward corporations with more liberal policies, making technological companies, for example, a leader in recruiting young talent. "The challenge for business leaders today is harnessing the talent and drive of the younger workforce." As the workplace changes, companies need to reconsider how they lead people and "get work done" while they're evolving, says Ty Kiisel at Forbes.

What do older workers think about this trend?
They hate it. The demands from younger workers come "much to the annoyance of older coworkers who feel they have spent years paying their dues to rise through the ranks," says Kwoh. Call it a clash of generations: A 2010 study showed that baby boomers "cited work ethic, respectfulness, and morals as their defining qualities," while "millennials chose technology, music and pop culture, and liberal leanings."

Is this a good thing?
Perhaps. "If we're smart, we'll cheer them on," says Matchar. Americans work longer at the office than citizens of other developed countries, while wages have flat-lined and benefits have been reduced. "The modern workplace frankly stinks, and the changes wrought by Gen Y will be good for everybody."

Sources: CNNForbesMedia Daily NewsThe Wall Street JournalThe Washington Post