What is Airbnb? In a nutshell, it's an online marketplace for arranging or offering accommodation. The company does not own any of the real estate listings; it acts as a broker, receiving commissions from each booking.

"It was an experiment of sorts in the hope of maximising the income potential while I was studying," McCallum says.

Phillip O'Neill: Airbnb has become an entrenched and popular component of the Hunter's visitor economy

"Coming up to four years later it has close to 100 per cent occupancy; 2019 was the best year yet, with just 10 days unoccupied. We offer one-night stays with no cleaning fee which seems to set us apart. A high percentage of our guests are one-night stays."

And yet, with countless guests, he hasn't had a single issue; the apartment is always treated with respect and left in great condition.

"The majority of positive feedback we get is about the views and the proximity to some of Newcastle's best restaurants and cafes," he says.

Most of the guests are from Australia, however, he does occasionally get overseas guests and a few overseas exchange students. They get couples celebrating their wedding night as well.

McCallum's mother, Teressa, assists with the management and cleaning.

"We do all our own cleaning to keep the costs to our guest down. It can be challenging but it's a choice we make," he says. "Many people ask me about Airbnb and my response is always that it's been a great experience for me and the quality of guests far surpasses my expectations - I probably anticipated the occasional problem with Airbnb or a guest but can honestly say we've not had even one."

Newcastle, $199 per night, two guests

Pokolbin, $96 per night, up to four guests

Philip Reid is originally from Scotland and lives on Victoria's Mornington Peninsula.

"I work for an insurance company in Melbourne managing their project investments. The property we have is a holiday rental and I was looking for a better way to attract people to stay," Reid says on his decision to try Airbnb.

His Bergarac Villa in the Hunter Valley has now hosted more than 200 guests, with concerts and wineries providing a steady stream of visitors.

"The most popular aspect is probably the open fire in winter but, for tourists, the local kangaroos and wildlife are also major drawcards," he says.

His biggest challenge? Because he lives 1000 kilometres away, he can't easily pop in when things go wrong.

"A few years ago when I was living in Sydney I got a call from a bride to say that the curtain had fallen down. I'm not sure what had happened," Reid says.

"I made the five-hour round trip, fixed the curtain and everything was fine after that. I now have a great cleaner who manages to sort out most problems for me."

Wangi Wangi, $292 per night, up to seven guests

"Airbnb is the best way to experience a place and to really feel like you're at a home away from home," says Emma Outteridge of The Boathouse in Wangi Wangi.

Originally from New Zealand, Outteridge spent her life travelling the world working on sailing events. During the 2013 America's Cup in San Francisco, she met her now husband, Nathan, a professional sailor. They spent several years globetrotting and quickly tired of living in hotels. They decided to only stay in Airbnbs.

"Nathan grew up in Wangi and bought the boathouse before we met and we would often come back to Australia to visit his family," she says.

"In 2014 we decided to do a complete renovation on the house and make it our own. By the time we'd finished the renovations in 2015, it was time for us to move to Bermuda for the next America's Cup, so it made sense to put the house on Airbnb. That way, when we come back to Australia for holidays, we can still enjoy our slice of paradise."

Their house is located on the lake with north-facing views across the water and a waterfront reserve.

Outteridge says she loves the view and the open-plan layout. The original house was very closed off and boxy with lots of small rooms, so the pair knocked out all the walls in the front half of the house. Now they have one lovely big room with uninterrupted views across the lake.

Outteridge runs a sponsorship program in Uganda, so the home has touches of Uganda - as well as sailing memorabilia from their travels. Because they live in Auckland, New Zealand, and travel, the biggest challenge is keeping on top of the different time zones.

"I often get messages in the middle of the night, depending on where I am. Luckily, thanks to our one-year-old son, I am often up in the night so can keep on top of things," she says.

The lake will always be her second home, and the couple love that they still get to return to it.

"What I didn't anticipate was how much enjoyment I'd get receiving all the messages from guests telling me how much they're loving our home; that they've seen dolphins jumping in front of the house; that the kids are having a blast; that they've poured a glass of wine and are sitting admiring the view," Outteridge says.

"It makes me feel like I still get to enjoy this gorgeous part of the world even when I'm on the other side of the world. I feel very lucky."

Charlestown, $75 per night, two guests

Rob and Lynne Branham have been Airbnbing for at least three years now. Lynne is a cardiac rehab nurse and Rob works as a chaplain at Wallsend Primary School. The pair spent 12 years living in Alaska (Rob is from the US) and Lynne grew up on the property where the Airbnb is located.

Their Kookaburra cabin is a short walk from Charlestown Square about halfway between the beaches and Lake Macquarie.

"We began Airbnbing because of a friend of ours who was putting in our front driveway," Rob says.

"He took one look at the cabin we had built for our children to come from the US to stay in, and said we should not let it just sit empty but we should Airbnb it."

The couple were unsure at first, but their friend convinced them to try it for just a month, telling them they'd meet great people and guests would love the space. They've been Airbnbing ever since, although their children and grandchildren get first priority. The cosy cottage is a self-contained cabin made completely of wood.

"It is private and even though it is in our backyard it can feel like you are miles away from anything," Rob says.

"The kitchen and bathroom seem to be highlights for people. I think people are surprised that the cabin has everything you need. We do have some guests that never leave the cabin."

They have received positive reviews and have accommodated every kind of guest. One couple came to meet their labrador Charlie. Another time Rob and Lynne donated a weekend away for a local school fete and the family who won had recently lost a loved one.

"It meant a lot to us to offer a friendly face, a sympathetic dog, a private place and space to breathe even if just for a weekend," Rob says.

Clearly the pair love being able to show off their little bit of paradise and its surrounds. Rob reckons it is the best-kept secret in Australia.

"We have lived in a few different places from Central US, Alaska and here, and hands down we live in the best place on earth," he says.

Vacy, $240 per night, up to four guests

Chris Murphy is a stay-at-home dad who moved to Maitland in 1995 as an electrical engineer and has since moved on to a career in IT.

In 2018 he and his wife were looking for a holiday house to share with their daughters. What they found was a gorgeous house that was already a successful business, thanks to the previous owners, with an enviable reputation on Airbnb.

Inala Wilderness Retreat is part of Eaglereach at Vacy and sits atop Mt George, with uninterrupted farmland views to the north for about 50 kilometres to Barrington Tops. The house is all glass on the north side, so every room soaks up the view.

"It's all about that view," Murphy says.

"The clouds usually march from left to right across that great panorama and every time you look out it's different. In winter there can be nothing to see as the mountain is enveloped in cloud. It's close and cosy and the log fire in the lounge room becomes a great substitute for the view.

"Summer or winter, the house's private outdoor spa is a great spot. I like to darken the house, lie back in the spa and count satellites at night."

Set up with one or two bedrooms with either a king and two singles or two king beds, the house usually appeals to couples or families with young children.

"People mostly come to unplug, which makes me question if providing internet access is a good idea," Murphy says.

Native animals like kangaroos, wallabies, lizards, goannas and snakes roam the property and its surrounds. Some lucky guests have spotted echidnas and koalas. Inala is private and quiet, but it's not isolated. Eaglereach Wilderness Resort contains about 40 houses which share the bush, lagoon, tennis court, pool, playground and games room.

"I like managing the Airbnb business. It's about a 45-minute drive from my home in Maitland and I can easily 'flip' the house in the four hours between a 10am check-out and 2pm check-in," he says.

"We pride ourselves on a spotless house with crisp white linen and towels. We keep the spa sparkling clean."

His biggest concern about going into Airbnb never eventuated.

"Our guests really are no trouble. People who stay at Inala look after the house like it's their own. If a guest needs something I just drop everything and go, but it's rare for that to happen," Murphy says.

His only downside is having to think ahead when planning his own family holidays.

"It's popular enough that we really do have to reserve our own place well in advance," he says.