Twenty-five years ago only 15 percent of U.S. households had a personal computer, and the Internet as we know it was a newborn.

Amazon.com, Google, YouTube, LinkedIn, Facebook and Twitter didn't exist, and mobile phones were just that—phones. Not handheld computers with Web access to games, movies, books, apps, stores, workplaces and bank accounts.

Along with the mushrooming growth and evolution of technology in the past quarter century came the generation of new occupations—and not only in the Internet realm. Advances in medical, computer and green technology, coupled with market demand for new products and services, have given rise to new types of jobs.

Defining a new occupation isn't necessarily easy, however, as old jobs often evolve to adapt to new technology. Is paid blogger, for instance, really a new occupation or simply a writer who now writes for websites? The U.S. Bureau of Labor Statistics hasn't officially classified blogger as a new occupation, but the agency published an article in 2012 called "Bloggers and webcomic artists: Careers in online creativity" about jobs for "digital media workers."

"Is it jobs that didn't exist, or work that didn't exist or workplace titles that didn't exist?" asked labor economist Linda Barrington, executive director of the Institute for Compensation Studies at Cornell University's Industrial and Labor Relations School.

"Clearly, occupations and jobs have changed a lot," she said. One sign of this is that the BLS is planning a substantial overhaul of job classifications for 2018.

We're also in an era when employees and entrepreneurs sport creative labels, such as chief marketing dragoness, marketing geek, content wrangler, entreprenerd, passionista and hambassador, to name a few.

But after conducting expert interviews, combing government data and other publicly available information about the job market, here is a sampling of notable occupations that didn't exist—or didn't exist in the same form or to a significant extent—25 years ago.

—By Dinah Wisenberg Brin, Special to CNBC
Posted 29 April 2014

This occupation may not have its own BLS designation yet, but there's no denying its emergence in the age of Twitter, Facebook, Pinterest and Instagram.

"Anything that has to do with social media, companies having a social media strategist—that was a job that never existed, because there was no social media," Barrington said.

One social media strategist said on LinkedIn that she helps companies "engage and build exposure using social media networks," a job that includes assessing client needs, developing strategy and measuring the results.

There wouldn't have been high demand for this service in 1989, the year the World Wide Web came to be.

It would be a few years until Amazon.com launched, and a few more before brick-and-mortar stores rushed to add "dot com" to their names.

These jobs now exist in a variety of settings, from independent to large e-commerce consultancies or marketing firms, and major retailers and brands that hire in-house experts.

The BLS designated "web developers" a new detailed occupation in 2010, broken out from the earlier "network systems and data communications analysts" category. But further changes may be needed, given the rise of smartphones and tablets.

Those who develop games like Angry Birds and Fruit Ninja for mobile devices and who enable company websites to function on smartphones and tablets are in demand.

"That's something that we know is a new job, because we know that mobile apps didn't exist 25 years ago," said Barrington. And mobile devices didn't have the computing functionality they have now, said Dino Grigorakakis, vice president of recruiting for Randstad Technologies.

"A lot of companies really want to be enabled in the mobile platform," Grigorakakis said. Banks, job board businesses, newspapers—"just about anybody you can think of that has a website that gets a lot of traffic"—want their websites to function on tablets, he said.

Most large companies hire their own in-house teams, but many outsource, Grigorakakis said. "There's an extreme shortage of these people, and often customers have to go to consulting firms because they're the only people that have skills available."

These occupations have "taken off like crazy" in the last two or three years, Grigorakakis said, explaining that "this skill set is extremely hard to find. This is a skill set that definitely didn't exist 25 years ago; it didn't even exist five years ago."

Powerful open-source batch-processing platforms, such as Apache Hadoop, allow researchers and businesses to search multiple servers at once. The result is a "truly transformational" development that has put big-data architects in high demand, according to Grigorakakis.

With this technology, a large insurance company, for example, may pull together and analyze data from different departments to discover new connections, such as that homes with backyard pools have higher burglary rates because people leave the back doors open, he said.

A big-data architect can set up the tools so business intelligence analysts can go and analyze the data, he said. There were 18,000 such jobs posted online in January 2012, a 35 percent increase from the previous year, Grigorakakis said. The BLS recently published an article on working with big data.

Large and small companies alike have been turning to cloud computing, or software as a service (SaaS), for a variety of needs—outsourcing entire functions rather than buying on-site servers and programs to perform the same jobs and hiring staff to service the technology, like companies previously had to do.

Customer relationship, human resources and supply-chain management are three areas where SaaS has made inroads.

"Cloud computing is enabling companies to do more with their IT spend[ing] than they could have 10 years ago because they don't have to put out huge capital investment," Grigorakakis said. "For small start-ups, the cloud has been huge."

Network or systems engineers who know how to integrate an external platform, like Salesforce.com, with a company's internal systems are working in cloud computing, Grigorakakis said. Other cloud-computing industry job titles on LinkedIn include cloud-computing sales specialist, consultant, executive, software engineer and guru.

In the BLS' 2010 classification system update, one third of "new" occupations occurred in the health-care practitioners and technical occupations group. Among these newly designated occupations are genetic counselors.

Genetic counselors assess individual or family risk for various inherited genetic disorders and birth defects, providing the information to other health professionals and patients and advising patients and families. People in this field, the BLS said, include prenatal genetic counselors, chromosomal disorders counselors and mitochondrial disorders counselors. Jobs like genetic counselor arise from a combination of scientific or technology advances and consumer demand, according to Barrington.

With so much business being generated on the Web, a company's placement in search results is critical. Employees who understand how to optimize Web pages so a company's website lands higher in Google and other search-engine results are key to generating and sustaining business, according to Grigorakakis.

The job of the search-engine optimization, or SEO, has developed over the past decade and is a cross between IT and marketing.

Thousands of LinkedIn profiles contain the term SEO in the job titles or skill descriptions, and the Monster job board advertises dozens of full-time SEO positions.

Not an entirely new job, unmanned aircraft systems operation is expected to boom in coming years as the government integrates drones into the National Airspace System and industries seek to use them for commercial purposes.

UAS have operated on a limited basis in the National Airspace System since the early 1990s, mostly in military and border security operations, the Federal Aviation Administration said in a report last year.

"The list of potential uses is now rapidly expanding to encompass a broad range of other activities, including aerial photography, surveying land and crops, communications and broadcast, monitoring forest fires and environmental conditions and protecting critical infrastructures," the FAA said.

Amazon CEO Jeff Bezos has said the online retailer is exploring the possible use of aerial drones to deliver goods to customers.

A study by the Association for Unmanned Vehicle Systems International predicts the industry will generate nearly 104,000 jobs by 2025 as a result of drone aircrafts' anticipated integration into the national airspace.

It's unclear what new occupations may emerge in this nascent industry, or whether existing jobs from other industries will change dramatically enough to officially qualify as new occupations.

But recent job postings offer a sense of what may be on the horizon. One business recently advertised online for a food scientist "to be hands-on in preparing, testing and qualifying edible formulas for use in 3-D printers."

Openings also were posted for a 3-D production repair technician and for a process-development engineer to work in a lab, helping to develop 3-D printing systems and processes involving new materials.

In one sense, this job may be as old as windmills. The BLS's move, however, to add it as a new detailed occupation in 2010, split from an earlier occupational category and corresponds with the relatively recent rise of wind energy in the United States.

Also known as windtechs, these workers install, maintain and repair wind turbines, making about $46,000 a year. There were 3,200 windtechs in the country in 2012, a number expected to reach approximately 4,000 in 2022, which the BLS calls much faster growth than average for all occupations.

"Because wind-electricity generation is expected to grow over the coming decade, additional technicians will be needed to install and maintain new turbines. Job prospects should be excellent for qualified candidates," the BLS said.