Who wants to work 40 hours a week for a single employer? In the future, perhaps nobody.

The full-time job, used to it as we are, is not some natural state of human existence. Before the 1800s, few people worked a structured “work week.” That conceit was dreamed up by early industrialists, who needed to bring workers together in a factory at the same time to efficiently make products. For the past 100 years, the 40-hour job has been the centerpiece of work life because there was no better way for people to gather in one place at the same time to connect, collaborate and produce.

But technology is now changing the nature of work. The trend points to a new era in which most of us will work in multiple “micro-careers” at the same time, leaving the traditional full-time job behind. “Work” is likely to turn into a marketplace in the cloud rather than a desk and a chair at a traditional corporation. A free agent workforce will be able to make a good living layering a number of professional relationships, entrepreneurial passions and other money-making pursuits on top of each other.

We’re already seeing the embryonic version of this kind of labor market, mostly focused on simple, hands-on work. Lyft and Sidecar are platforms that give people a way to leverage their cars and time to make money. TaskRabbit is a market for odd jobs. Airbnb lets you rent out the extra room in your home. Etsy is a market for the handmade skirts you sew while watching Game of Thrones.

The big change, though, is that this manner of work is going professional. Instead of side gigs, people will be able to instantly market their expertise in engineering, law, chemistry, writing or anything else to an array of clients, assembling a well-paid career as a multi-faceted free agent.

One General Electric program shows how that can play out. In 2013, GE opened up a public contest called the Bracket Challenge. Their jet engine division needed a new lightweight design for brackets that would help hold an engine on an airplane. About 700 people from all over the world submitted designs. GE chose one by M Arie Kurniawan, an engineer living in Indonesia. Kurniawan won $7,000, and GE got a part that’s 84 percent lighter than its predecessor.

The program was such a success that GE plans to launch many more design challenges in coming years. Other companies, from drug makers to oil drillers, are creating similar initiatives. In his book Wikinomics: How Mass Collaboration Changes Everything, author Don Tapscott describes how porous companies will increasingly open work to the crowd. As that happens, a new kind of market will emerge that lets people apply their expertise to many companies all over the world.

A start-up called Recruitifi illustrates another way that professionals will be able to leverage their networks and competencies for financial gain. The core purpose of the company is to create a platform for the recruiting industry. Its technology pools all kinds of headhunters on one side, and corporate clients on the other, much the way Lyft pools drivers on one side and riders on the other, with a clever app in between.

But there is an intriguing by-product to Recruitifi: Pretty much anyone can become a recruiter. “There is really no barrier to entry,” CEO Brin McCagg told me. So let’s say you’re a marketing manager. You probably know other good marketing managers. You could set up an account on Recruitifi, keep an eye on the demand for marketers and propose candidates for openings. If your candidate gets hired, you’d get paid. Now you have a new line of work that’s monetizing your network.

Upwork (until recently Elance/oDesk) is a pure market for free agent work, letting any entity find and hire professionals for almost any type of knowledge-based work. Meanwhile, new tools are making it cheap and easy to start a business, allowing people to be part-time entrepreneurs. DigitalOcean makes it simple to build a smartphone app and set it up as a stand-alone business. Shapeways allows someone to design a product and have it 3D printed and sold worldwide. While Amazon Web Services and other cloud services companies have driven down the cost of hosting a digital business and distributing it around the globe.

All these developments are making it possible for a typical professional to have a multi-faceted career with several sources of income. He or she can maybe do some recruiting, build a business and take on projects posted by corporations — all at once. The work week can be as many hours you want, with whatever schedule you desire.

But even as this new labor market promises us greater flexibility, we don’t yet know if it’ll make us work any less. History is full of predictions that technology will shorten work hours. A 1965 Senate subcommittee predicted Americans would work 14-hour weeks by 2000, with seven weeks of vacation. Instead, we have the most advanced technology but some of the longest hours in the world.

And while this kind of dynamic, entrepreneurial life may horrify an older generation, we already know that younger workers tend to prefer their work to be more ephemeral. The mindset of long-term full-time employment is clearly fading: A recent Future Workplace survey found that 91 percent of millennials expect to stay in a job for less than three years, and that flexible hours and location-independent policies are more desirable than salary.

In fact, an organization called Live in the Grey asks why anyone would want a single job that eats up 40 hours a week. It refers to itself as a collection of “disruptors, innovators and thought leaders that believe life and work are not black and white,” and its supporters include Pepsi, Warby Parker and Lululemon. Better to piece together work and passions in a way that makes you enough money and offers a more rewarding life.

As we march into this new future, perhaps now is the time for graduating students to ask themselves what kind of career they want: a traditional full-time job with a single company or a series of overlapping micro-careers. And more importantly, how does one set oneself up for success in this nascent economy?

Illustrations by Anna Vignet