The Instant Pot, a high-tech kitchen appliance created by former Nortel engineers in Ottawa, was not, in the beginning, an instant success.

Founder Robert Wang, a one-time chief scientist for Nortel, began work on the multi-functional electric pressure cooker after the tech giant began winding down its research and development work during the financial crisis of 2008.

"We started looking at consumer products. Trying to apply our skills and knowledge to create a product which [would] appeal to other consumers," he said.

Invented in Ottawa in 2010, the latest incarnation of the Instant Pot is equipped with a microprocessor that allows it to perform complex functions.

The appliance originally was sold in stores, but there wasn't much marketing promoting it, said Wang.

The company began selling the Instant Pot on Amazon in December 2010, and that's when things slowly got cooking thanks to an old-fashioned ingredient: the consumer review.

Became Amazon top seller in 2013

"My guess is that somebody bought it and they told all their neighbours about it," said Kim Whitler, an assistant marketing professor at the Darden School of Business at the University of Virginia. "They buy it and they're really wowed by the product. That then motivates them...to go online and share their experience with others."

Kim Whitler

Business professor Kim Whitler says consumers are more likely to believe recommendations that come from other people rather than companies. (Supplied)

The Instant Pot began outselling stove-top pressure cookers on Amazon in January 2013, it has continued to do so since, and has now sold two million units worldwide.

Amazon sold 215,000 units last year on one day alone: Prime Day, a sales event where some Amazon members get access to exclusive deals.

Although the one-day event has long passed, the cooker continues to be a top seller on the company's U.S. site, with over 15,000 reviews — 93 per cent of them positive.

"The average rating is four point seven. This is unheard of," said Wang.

Whitler said successful word-of-mouth campaigns happen when products give customers what they promise. "If you make a big promise you have to have a very big delivery."

Credibility, Whitler says, also plays a big role in influencing people's buying decision.

"When you receive a recommendation from somebody who receives no economic value from delivering that recommendation means more."