How data is saving the retail industry

But while mall stores struggle, fast-fashion giants such as H&M, Zara, and Forever 21 are thriving.

This is in part because of strategies that are based in data and analytics. By understanding what the consumer is craving, these companies can drive sales.

This is not a new phenomenon.

"Fashion, especially 'mass fashion' has always been about data," Anush Prabhu, Partner and Chief Channel Planning and Investment Office at advertising agency Deutsch said in an email to Business Insider. "Retailers see what designs/products of some of the more expensive designers are selling and they then create 'reproductions' of those designs/trends. For example,when a quilted bag from Chanel is seen to be trending, a Forever 21 or Kate Spade comes out with quilted bags that are similar."

Fast fashion companies know the importance of curating data more than anyone.

"Retailers, especially fast-fashion retailers, are always at the forefront of innovation because they work with razor thin margins and are more focused on the direct results/performance of ads than any other group," James Green, CEO of Magnetic, a company that specializes in providing data to marketers, said to Business Insider.

And the more information that's available, the easier it becomes.

"Today, given the extent of data available, retailers in fashion can be a few steps ahead of the game - for example, they have access to millions of conversations in social media and can be more predictive of what is going to catch on before it does," Prabhu said. "Access to shopper behavior based on weather, mobile data on store visitation, etc. can be capitalized on further to change the game. For example, retailers like Gilt a few years ago started focusing around the time of day when in office browsing activity was the highest - activating against that data changed how people shopped for fashion online."

And perhaps more obviously, when an e-commerce retailer "suggests" items for shoppers to buy, it utilizes data based on the shopper's browsing and search histories.

Further, this data can also help companies create intelligent, specific marketing campaigns.

"Remaining on the cutting edge involves running advertising campaigns that are knowledgeable about the customer base; these campaigns cannot simply show different ads to different folks based on their "intent," but also need to target consumers based on their past purchase behavior, loyalty and other data," Green said.

For example, this could include using information to create a consistent tone.

"Combining customer information with advertiser outreach is critical for reaching the correct consumer base for a few reasons: First of all, consumers have grown to expect a consistent experience from all brands - and are increasingly happy when technology provides a solution without being prompted," Green explained. "We see this when Google sends an alert reminding you about your next appointment; for a retailer, it is more subtle but just as compelling. Telling someone that the product they bought six months ago is currently on sale is now a well-received tactic by consumers. The opposite effect occurs when a consumer is still receiving special offers for that H&M bag, the Topshop coat, or any other product that has already been bought. The likelihood of this annoyance happening is reduced or even eliminated if advertising is tied to a CRM system."

Another way to make sure retailers don't have misfires is to utilize testing and cull the results for information.

One brand that executes this practice is Adore Me, a fast-fashion lingerie company that has experienced tremendous growth. It was named Inc.'s No. 2 retail company and No. 14 overall company on its prestigious Inc. 5000 list. Inc., which notes that in three years, the company has grown a whopping 15,606%.

Just look at the numbers: in 2012, the company brought in $1.1 million. By 2013, the company brought in $5.6 million. And in 2014, it raked in $16.2 million. (To put it in perspective, this summer, director of business and brand development Sharon Klapka told Business Insider it was on track to out-sell lingerie stalwart La Perla.)