Is there a real threat to Airbnb now? Could be.

It seems more pod hotels are popping up across the globe, with New York and London joining the bandwagon. Pod hotels, if you have never heard of the term before, are inexpensive hotel rooms that are quite tiny in size — hence the term pod. They take up less space, use fewer resources and cost way less than a regular hotel.

The idea originated in Japan, which is one of the most expensive places to live and work in. These tiny hotel rooms made perfect sense for business travelers and young people who wanted to stick to a budget. They have been prevalent in Japan for more than three decades, but the idea is just gaining popularity now in the West.

As a cheaper lodging option, they may take on Airbnb sooner than later.

New York City is in love with the idea of pod hotels. Pod 51 in Manhattan was the first to open with its well-appointed rooms. Then came Pod 39 with its 120-square-foot rooms in what used to be a Salvation Army shelter for the homeless.

The latest name to join the microhotel trend is Williamsburg Brooklyn. The module pods will be made in Poland and then shipped to the U.S. to be assembled into a 250-room pod hotel.

Rents for these compact rooms start at just $99 a night — incredible for Manhattan. The hotel also boasts a bar and a sitting area along with a modern and spacious lobby.

In London, the newest pod hotel will also be an underground hotel. Slated to be built under St Giles Hotel in London's West End, the microhotel will be designed sustainably with plants all over, bright rooms and wood paneling. Though it will be underground, it will reportedly have a mechanical ventilation system for air purification offering air that's cleaner than outside.

Using up the fourth and fifth floor underground parking lot, the hotel can house up to 166 guests at affordable prices. The design will be similar to the Japanese pod hotels, except it will add a toilet and shower in the room.

There are some excellent reasons why these microhotels are growing in popularity around the world. According to a recent Conde Nast Traveler article, this matches the mindset of modern-day travelers. Millennials are adventurers who spend little time in their rooms. The idea that they are directly contributing to saving the planet by staying in these sustainable hotels resonates well with them.

Besides, this is what the industry may need right now. Low construction costs that balance well with low maintenance costs will go a long way to bring the lodging industry back in the black. Marriott opened a Moxy hotel with tiny rooms in Milan in 2015, and Hollywood will be sporting "lifestyle microhotel brand" in 2018.

In the next year, Chicago is all set to join the trend, too. A major hub for national and global tourists, Chicago is not exactly known for its reasonably priced hotel rooms. Microhotel rooms from various hotel chains may change that and soon.

The concept is not just lower room rates and sustainability but also paying for only what one uses. Guests have the option to choose from the many facilities, both in-room and common, and thus stick to their budget.

Travelers can enjoy a novel experience, get all the amenities they need yet not pay what staying in an expensive city entails. Adjustable beds and closets, efficient storage options and built-in smart technology may soon turn the trendy pod hotels mainstream.