In the fifth annual Disruptor 50 list, CNBC features private companies in a range of industries — from biotech and machine learning to transportation and retail — whose innovations are changing the world. These forward-thinking starts-ups have identified unexploited niches in the marketplace that have the potential to become billion-dollar businesses, and they rushed to fill them. A startling 31 are unicorns that have already reached or passed the billion-dollar mark. In the process, they are creating new ecosystems for their products and services. Unseating corporate giants is no easy feat. But we ranked those venture capital–backed companies doing the best job. In aggregate, these 50 companies have raised nearly $44 billion in venture capital at an implied Disruptor 50 list market valuation of about $239 billion, according to PitchBook data. Already it's hard to think of the world without them. Read more about the consumer and business trends that stand out in the 2017 list ranking and the methodology used to select this year's Disruptor companies.