Would you have heard of user experience designers before the turn of the millennium? How about a search engine optimisation specialist? Or social media analysts?

Chances are, these jobs - which are increasingly in demand these days - probably did not exist or were unheard of 15 years ago.

Since 2000, new jobs such as app developers, social media officers and search engine optimisation specialists - who help businesses increase their rankings on online search engines, typically by assisting in the business' web design - have popped up.

Singapore's Economic Development Board has also identified data analysts, user experience designers, design or innovation managers, design researchers and futures advisors as new jobs in the past 15 years. Some of these jobs emerged due to technological developments, while others, such as sustainability officers, came about because of rising environmental awareness.

The emergence of new jobs is not surprising, say experts. What is interesting is the variety and speed at which they are entering the mainstream labour market.

Mr David Leong, 45, managing director of recruitment firm PeopleWorldwide Consulting, says: "As technology advances, new jobs will emerge to replace older ones relying on existing technology.

"But with technology advancing at a faster rate, the labour market has probably changed more in the last 15 years compared with the 50 years before that. It looks like it might change even more quickly in the future."

Experts say the biggest influence on the job market in recent years is probably the Internet explosion.

Although said to have been developed as early as the 1960s, the Web saw mass adoption in the late 1980s and 1990s and has since influenced almost every aspect of life.

The Internet's exponential growth, fuelled by the development of mobile devices such as smartphones, has also led to the rise of related technologies such as social media. Some milestones - Google was founded in 1998, Facebook was launched in 2004 and the first iPhone was released in 2007.

More than three billion people - 43 per cent of the world's population - use the Internet, according to the United Nations International Telecommunication Union.

Says Associate Professor Sarah Cheah of the National University of Singapore Business School: "From being a unique medium for locating and exchanging information, the Internet has evolved into a main platform where e-commerce takes place and peers connect with one another through social networks. The Internet's appeal to consumers has surged to unimaginable heights.

"It is, therefore, not surprising that companies and agencies have introduced new organisational processes, structures and roles to capture the burgeoning e-commerce market."

And for many businesses and organisations, social media has become a crucial element of their customer-engagement strategies.

Banks, airlines and government agencies hire executives to handle their social media accounts.

For example, when OCBC Bank set up its Twitter account in 2011, it was managed by one employee. Today, it has more than 10 full-time staff working on platforms such as Facebook, Instagram and LinkedIn, and handling aspects such as strategic planning and governance, brand management, content marketing and customer service.

Other jobs that have rode the technology wave include app developers and search engine optimisation specialists, who can be employed by companies or operate as independent contractors.

Apart from technological advancements, experts say a growing awareness of environmental issues in recent decades has led organisations to employ a sustainability officer to champion and monitor sustainability efforts.

For example, under a government initiative last year, each ministry is required to appoint a sustainability manager to drive sustainability improvements within the ministry and its statutory board, among other tasks.

Mr Erman Tan, 51, president of the Singapore Human Resources Institute, says: "In the past, responsibilities involving sustainability rested with the facility manager.

"But as sustainability initiatives have now expanded beyond the facility - to include the company's overall strategy and product marketing philosophy - the position has increased in importance and now has its own title."

So what does the emergence of new jobs mean for job seekers?

Polytechnics and universities say they are aware of the changes in the job market and are preparing their students to take advantage of new opportunities.

For example, in 2011, NUS introduced a multi-disciplinary environmental studies degree programme to produce professionals with the skills to understand and address complex modern environmental issues.

That same year, Singapore Polytechnic introduced a module on social media marketing to prepare its business information technology students for new jobs such as social media officers.

Last year, the school also launched a social media listening centre in its premises so that students can learn how to use social media monitoring tools, manage a company's online reputation and execute a social media marketing campaign.

In 2012, Ngee Ann Polytechnic started a digital media communications specialisation option - which includes modules such as social media strategy, content design for mobile devices and integrated digital media - under its diploma in mass communication.

In recent years, Nanyang Polytechnic has also introduced courses in mobile computing, analytics, social computing, cyber security, Internet and cloud computing, to equip students with the skills to meet the changing needs of the working world.

Its specialist diploma in mobile computing, introduced in 2013, and its diploma in infocomm and digital media, introduced in 2011, are over-subscribed.

Mr Dennis Ang, director of the polytechnic's school of information technology, says: "To address future industry needs, Nanyang Polytechnic constantly keeps abreast of the ever changing industry landscape through our strong links and collaborations with the industry.

"We also have industry leaders on our advisory committees to provide feedback and advice on current and future trends. Their feedback helps shape our curricula to ensure that our students graduate with the relevant industry skills and knowledge."