Headquarters: Seattle, Washington Year founded: 1994 Why it's revolutionary: In January, Amazon opened its first cashierless store, Amazon Go, in Seattle, which promised to create a completely slick shopping environment by using cameras and sensors to enable customers to purchase items without having to go to checkout or wait in line. Shoppers are automatically charged when they leave the store with an item. There are now four of these locations in the US; Amazon reportedly plans to open 3,000 more in the next few years. Read more: I shopped at Amazon's cutting-edge convenience store without registers or lines, and now I'm convinced it's the future of retail — for better or for worse Headquarters: Bentonville, Arkansas Year founded: 1962 Why it's revolutionary: Walmart has been on an acquisition spree in the past few years, buying up popular e-commerce brands in an effort to woo millennial shoppers. In 2018, these included online lingerie site Bare Necessities, plus-size retailer Eloquii, and Art.com. A Walmart spokesperson told Business Insider that one of the drivers for customers to continue coming back to your brand is going to be finding products and experiences that they just can't get anywhere else. With these new trendy brands, it hopes to do just that. Walmart's e-commerce president and CEO Marc Lore also said the retail giant needs to acquire 40 to 50 successful digitally native retailers in order to resonate with millennials, so consumers can expect more to follow. Headquarters: San Francisco, California Year founded: 2010 Why it's revolutionary: Apparel brand Everlane has built its business around radical transparency and creating high-quality clothing through ethical processes. In October, it took this a step further by launching a collection of jackets that are made entirely from repurposed plastic bottles. Everlane founder and CEO Michael Preysman said that the brand plans to completely eliminate non-repurposed plastic from its supply chain by 2021. Headquarters: New York, New York Year Founded: 2013 Why it's revolutionary: Hot on the heels of opening its first store in New York in February, Casper opened the Casper Dreamery, a new sleep store where customers can come for a quick power nap during the day. The beds are kitted out with Casper mattresses and pillows to give customers the chance to trial its products. A 45-minute nap costs $25. Read more: Mattress startup Casper just opened a new space where you can pay $25 to take a nap — here's what it's like to visit Headquarters: Pittsburgh, Pennsylvania Year founded: 2006 Why it's revolutionary: Aerie is leading the charge in body-positive fashion advertising. In 2014, it swapped its airbrushed ads for unretouched photos and launched a campaign known as #AerieReal, which promoted natural beauty. And it's working well. In December, its parent company American Eagle reported a 32% increase in same-store sales numbers at Aerie. Group CEO Jay Schottenstein described this as one of the company's best results ever in a call with investors after the earnings release, marking its 16th consecutive quarter of double-digit positive growth. Read more: We shopped at American Eagle's Aerie store and saw why it's achieved explosive successHeadquarters: Menomonee Falls, Wisconsin Year founded: 1962 Why it's revolutionary: Kohl's has been one of the few department stores to come out of the retail apocalypse unscathed, and analysts say this is partly due to the innovative changes it has brought to its stores. This includes a new partnership with Amazon to sell the e-commerce giant's devices in stores and offer a free returns service for products bought on Amazon at certain locations. CEO Michelle Gass said that the partnership is mutually beneficial: Kohl's has access to new customers, and Amazon gets access to physical locations. Read more: Kohl's is being hailed as a winner of the retail apocalypse while other department stores struggle. We shopped there and saw why.Headquarters: New York, New York Year founded: 2009 Why it's revolutionary: Rent the Runway is a fashion company that allows customers to rent clothing from more than 600 different designers, wear them, and then return them. Prices range from $30 for a one-off rental to $159 a month for an unlimited subscription. The company now has more than nine million members and is reported to be valued at around $800 million. A spokesperson for the company told Business Insider that Rent the Runway now ships to 76% of zip codes in the US.Headquarters: New York, New York Year founded: 2012 Why it's revolutionary: Peloton has revolutionized home fitness. Its core product, the $1,995 high-tech indoor bike, has built a cult following of fans with its live classes that can be streamed from home. In January, the company unveiled its latest product, the treadmill, which also offers customers the chance to log in to live fitness classes. The company was valued at $4 billion after it closed a $550 million financing round in August. Read more: We tried the new $4,000 treadmill from the billion-dollar startup that could be 'the Apple of fitness' — here's the verdict Read more: New data says Peloton now has more customers than rival SoulCycle. We tested workouts from both — here’s the verdict.Headquarters: Los Angeles, California Year founded: 2007 Why it's revolutionary: Sweetgreen is passionate about making healthy fast food more accessible. Since launching in 2007, it has grown at a rapid rate — it now has almost 100 restaurants across the US and plans to open as many as 2,000 of its office pickup locations, known as Outpost, in the next few years. In November it raised $200 million in a new round of funding led by Fidelity Investments. The company is now valued at over $1 billion.Headquarters: San Francisco, California Year founded: 2013 Why it's revolutionary: Online bra retailer ThirdLove has made it possible to buy bras without having to go near a fitting room. Shoppers are asked to complete a quiz to determine their perfect bra shape. ThirdLove then ships three bra styles out to the customer, who is then able to trial these styles for up to 30 days. Cofounder and co-CEO Heidi Zak told Business Insider in September that more than 11 million women have taken the quiz, and that ThirdLove now has more than 600 million data points from this. The algorithm is getting smarter and smarter, she said. Read more: ThirdLove slams Victoria's Secret in full-page NYT ad Headquarters: San Francisco, California Year founded: 2009 Why it's revolutionary: Online thrift store ThredUp is leading the way in the secondhand buying-and-selling market. It's now the largest online secondhand store and has four stores in the US. Customers selling unwanted items are sent a clean out bag, which they send back to ThredUp to decide what can be sold and what will be donated. The seller is either paid upfront or on consignment. Cofounder James Reinhart told Business Insider that the store has 35,000 different brands and that fresh inventory and a wide selection are what keep customers coming back for more. In October, ThredUp launched UPcycle, a program that enables customers to donate clothing and turn it into cash to spend at trendy brands such as Reformation. Headquarters: Austin, Texas Year founded: 2014 Why it's revolutionary: Outdoor Voices is on a mission to become the world's No. 1 athletics brand, overtaking more established brands like Lululemon and Under Armour. In just under five years, 30-year-old founder Tyler Haney has built the brand from being an e-commerce-only platform to now having eight permanent stores in the United States. Earlier this year, the company raised $34 million in funding, bringing its total raised to $56.5 million. At the time, it said it would use the additional funding to grow its store count. Two more locations are slated to open this fall, and we can expect to see it spreading its reach throughout 2019.Headquarters: San Francisco, California Year founded: 2016 Why it's revolutionary: Online startup Brandless is encouraging shoppers to ditch well-known brands for its own-brand products. It sells basics— from pasta to hand soap and kitchen utensils — for a flat price of $3. The company raised $240 million earlier this year in a Series C funding round led by Softbank. Read more: Brandless, the online store that sells everything for $3, just got $240 million to take on Amazon. Here's what it's like to use.Headquarters: Paris, France Year founded: 1970 Why it's revolutionary: Sephora is making beauty high-tech. Its mobile app, Virtual Artist, allows customers to virtually apply lots of different types of makeup without having to even touch their face. If you find a look you like, it will tell you exactly which products are being used so that you can easily find them in store. Customers can try before they buy throughout the store, use the color IQ scanner to match colors to their exact skin tone, and even use a touchscreen fan to smell different scents.Headquarters: Beaverton, Oregon Year founded: 1964 Why it's revolutionary: Nike launched its new scan-to-buy feature this year. This new service, which is accessed via the app, allows customers to scan the barcode of an item in the store and instantly purchase it. Business Insider's Dennis Green crowned this the most exciting piece of technology to come to the retail industry this year. Read more: Nike gave us a glimpse into the store of the future this year Headquarters: New York, New York Year founded: 2014 Why it's revolutionary: After setting up a beauty blog, Glossier founder Emily Weiss decided to create beauty products based on reader comments and feedback. The company has attracted more than $86 million in funding since launching in 2013, and revenues reportedly tripled from 2016 to 2017. According to Bloomberg, the company sells one of its popular $16 Boy Brow eyebrow shapers every minute, accounting for an estimated $8 million in sales per year. Read more: Glossier, the wildly popular startup that's raised $86 million in its mission to revolutionize makeup and skin-care, just opened its first flagship store. Here's what it's like to shop there. Headquarters: New York, New York Year founded: 2015 Why it's revolutionary: Away wasn't the first company to invent smart luggage, but it has become a market leader. Its suitcases, which come in four sizes and cost between $225 and $295, come with a built-in charger. These suitcases have become the latest trendy item in travel. The company recently raised $50 million in funding and now has eight stores in the US and UK. Headquarters: New York, New York Year founded: 2013 Why it's revolutionary: Zola is changing the wedding registry industry. The site offers couples the option to register for gifts and experiences such as vouchers for Airbnb or Hotels.com, or to simply ask their guests for cash to go towards their honeymoon or other big expenses. It is fast becoming one of the leading disruptors in the market. In May, it announced that it had raised $100 million in funding from investors that included NBCUniversal and Goldman Sachs.