Do you have a job? If you do, you'll know the world of work can be tough – long hours, tedious tasks and stress. But it can bring benefits too, such as a regular salary and, sometimes, job satisfaction. Maybe that's why more us are now taking on a side hustle – another name for a second job.

For some having two jobs is a necessity – a way to make ends meet and provide extra income. But it now seems that more people want to put their skills and passions into practice to make money. These tend to be entrepreneurial young people who want to work on their own projects alongside their main source of income.

According to Henley Business School, around one in four workers run at least one side hustle business, half of which were started in the past two years. Those aged 25 to 34 are most likely to be involved, with 37% thought to run a sideline of some kind. It calculates that the average side hustler makes about 20% of their income through their second job.

But what's interesting is that many millennials are turning their hand to new jobs not just for money and security. Research has found that almost three-quarters of people are following a passion or exploring a new challenge. BBC News spoke to Becci Mai Ford, who works some of the time for a telecommunications company to pay the bills, but spends the rest of her time developing her crafting company Ellbie Co. She says going full-time is "not financially worth it right now but it fuels my creative soul and makes me happy."

Mobile apps have also aided the more commercially minded side hustler. Peer-to-peer firms such as Uber, Deliveroo, AirBnb and TaskRabbit allow users to do everything from odd jobs to renting out homes and parking spaces from their mobile phone.

Of course having a side hustle means you are self-employed - or freelance - which can give you flexibility to work when you like, but it can be risky. You sometime work on a zero-hours contract and may not get offered enough work. Or what was originally your passion may become more of a chore. However, this could be the best way to try out a new career or follow a passion while not giving up the day job.