Each e-commerce segment will have only one winner. Who will it be?

In another day and age, these young men would probably have been good friends, sharing meals and drinks, generally hanging out or just getting together for parties. They are remarkably similar in many ways - in terms of education, in their shared interest in technology, in their firm belief that e-commerce provides a way to disrupt traditional retailing models while serving the customer better, and finally in their shared ambition to create companies that become leaders in their fields. Most of them are today in their early 30s, and started their entrepreneurial journeys while they were still in their 20s. A couple of them are older - in their 40s - but they too are free spirits with the ambition of building something completely new. At least half a dozen of them even studied in the same institute - IIT Delhi - at almost the same time.

Over the past five years, they have built some of the best-known brands in Indian e-commerce, and raised the bar both in terms of customer service and in raising finances. A few of them run companies with a billion-dollar-plus valuation while others too have seen their valuations rise by the day. They are now running companies that have collectively raised more than $7 billion of funds including the $2 billion committed by Amazon's parent. They have revenues of $683 million, and are aiming to dominate the e-commerce market that is projected to grow to $102 billion by 2020.

As it happens they are not friends but bitter rivals fighting for supremacy in different online segments. Sachin and Binny Bansal of Flipkart are 33 and 32 years old and studied in IIT Delhi and worked in Amazon, though in different divisions, before they set up India's biggest online retailer. But snapping at their heels are Kunal Bahl, 31, who studied at Kellogg School of Management and the University of Pennsylvania, and his partner and co-founder of Snapdeal, Rohit Bansal, who too studied in IIT Delhi. It is very likely all the three Bansals knew each other at their alma mater, though Sachin and Binny hardly ever mention Rohit Bansal. The three Bansals and Bahl are also fighting another rival - Amazon India's Amit Agarwal. Amazon came into the Indian e-tailing scene fairly late, but Agarwal is as entrepreneurial and combative as they can get. Talk to any venture capitalist or e-commerce observer today, and they will tell you that one of these three companies will survive, while the other two will fade away.

Mukesh Bansal and Ashutosh Lawania studied together in IIT Kanpur and set up Myntra, India's first proper fashion e-tailing company, and now part of Flipkart. Praveen Sinha got an engineering degree from Delhi College of Engineering and a management diploma from IIM Calcutta. His partner Arun Chandra Mohan is an MBA from INSEAD and a venture partner at Rocket Internet. The duo set up Jabong, which is Myntra's biggest competitor, though Bansal and Lawania refuse to acknowledge that. Jabong and Myntra have pulled away from the pack in fashion retail and are acknowledged as the two biggest players in that field. Most commentators expect one to dominate, while the other will lose out.

Deepinder Goyal and Pankaj Chaddah, co-founders of Zomato, India's biggest restaurant listings company, are IIT Delhi graduates. They are now crossing swords with Rohit Chadda, who heads Foodpanda and studied at Delhi College of Engineering and IIM Calcutta. They started out with vastly different models of business, but are now stepping into each other's territories. There is likely to be only one man standing finally after this.

The OLX and Quikr founders are somewhat older than the rest of the lot, both aged around 40. OLX India's founder Amarjit Singh Batra spent a significant part of his career building Internet businesses. Quikr founder Pranay Chulet has donned various hats, including making a short feature film just before starting the company in 2008.

While the entrepreneurs behind Urban Ladder - Rajiv Srivatsa and Ashish Goel - are IIT and IIM graduates, their rival Pepperfry is run by Ambareesh Murty, a former eBay India country manager, and his colleague from eBay Ashish Shah.

The bitter battle for domination is because the e-commerce space globally is a winner-takes-all arena. In each category, there emerges one winner, while others fade away. That is something all the start-ups featured here know as well because e-commerce is a game of burning cash unless you become the absolute leader of the pack. It is only then that they can start making any money.

The fight has reached the crucial endgame because these companies have pulled away from the herd and now are aiming for the ultimate prize. They are also piling up losses, as they use investors' money to buy market share and customers. At some point, the money will dry up and only one winner can survive.