When she's not working her day job at a used bookstore, Brittany Jasper spends most of her time perusing consignment stores, yard sales and flea markets for clothing and accessories.

She's not really brand-loyal, since she can't afford the ones she likes at full price, "but secondhand isn't so bad." Instead, she tends to gravitate toward whatever fits her style and budget, which could be a pair of lightly used Banana Republic chinos one day or a vintage oversized tunic and tangerine leggings the next.

"I am drawn to things that are different, that I'm not going to be able to find just by shopping in the mall," said Jasper, 26, of Nashua, New Hampshire. "More than anything, it's about the look. I'm not afraid to pick up anything no-name if I like it."

It's a fairly conventional approach to personal style until she gets home, takes pictures of herself modeling the clothing and uploads them to Copious, an online marketplace that lets her share, buy and sell items. If she doesn't like pieces for herself, she posts them for sale on her page and shares them with followers from a variety of sources, including Facebook and Twitter. When someone "likes" a dress on Jasper's profile, her social media followers are notified, along with followers of the person who liked the dress, creating web of notifications that feeds back to Jasper's page.

It may sound complicated to the uninitiated, but Jasper is hooked, and not just because it's a place to buy and sell. She's used platforms like Etsy and Suvi, but none of them came close to the interactive community she has found on Copious, she said.

"I really like that it's so social and tied into the people you like and what you like and what you express interest in," she said. "It kind of molds itself around you."

Personalized shopping and browsing experiences

Technology and social networking distinguish Jasper and her peers from previous generations of shoppers in the eyes of brands, retailers and market researchers. By creating personalized shopping experiences around themselves, millennials are upending the traditional consumer-brand hierarchy, leaving brands and retailers scrambling to reclaim their influence.

"Millennials are at the forefront of the change in the retail landscape, based on their adoption of online and virtual behavior," said Ana Nennig, executive vice president of global consulting firm Havas PR.

"As the first generation that truly embraced instantaneous gratification, they mixed with that a desire to be fiscally aware of pricing and value and set the ground for shopping attributes (that) other generations and groups are adopting."

That doesn't mean millennials are completely brand-agnostic, Nennig said. They just put more time and effort into finding brands they identify with in terms of voice and social agenda. Conversely, brands are investing more of their identity into social agendas, from TOMS Shoes' "one pair sold, one pair donated" business model to west elm's collaborations with Etsy artists.

"For millennials, brands are an essential way of identifying, expressing and supporting what they find personally important. Using brands that embody their values makes them feel good," she said. "Retailers also need to keep in mind that millennials tend to seek brands and products that are socially responsible; this generation is looking for products that are sustainable, fair-trade and offer lower carbon footprints, for example."

On the whole, they're just as trend-driven as previous generations, said Samatha Bergeron, founder of market research agency Uncover, which performs consumer research for fashion and retail brands.

Millennials tend to have a wide knowledge of fashion, and how they act on that knowledge distinguishes them, she said.

"They're more fashion-savvy, not in terms of what they wear but what they know. You can go to Duluth, Minnesota, and find a girl who can tell you about Stella McCartney, and that's pretty much the norm where it might not have been the case in the 1980s," she said.

"But they're still taking direction; that hasn't changed. We're not a society that goes it alone," said Bergeron.

The rise of the 'curated' platforms

To meet these needs, brands and retailers are working furiously to create "seamless" experiences from stores to online portals. New social media networks and apps are emerging with the goal of delivering "curated" experiences.

"This is how millennials shop: They want experiences based on what's interesting to them," said Jonathan Ehrlich, co-founder and C)O of Copious. "What we're trying to do is organize a marketplace personalized and customized to you. You don't see a top-down curated experience; you see an experience related to your connections."

Copious entered the ever-expanding landscape of "curated" and "edited" online marketplaces in January with women's apparel and accessories. It expanded into menswear last week with the introduction of stylist and reality TV star Brad Goreski as one of its newest sellers.

"I think it can be really hard to distinguish between e-commerce sites. It often comes down to the basics. Can I get that bag on site X or site Z faster? Which one has free shipping? What's their return policy?" Goreski said in an e-mail. "Copious is building an experience that reflects individual style and taste, and I think that's really powerful. When I think about styling for my clients, I don't show each person the same dress, or the same handbag, or the same pair of shoes. I try to understand what best reflects their personality and taste."

It's also the latest example of a model that's threatening the traditional influence of brands and retailers. Instead of walking into Ann Taylor or Forever 21 for inspiration, some millennials are sourcing style cues from a variety of portals and social networks -- online and in real life -- and finding the version that suits their budget, Bergeron said.

"Relationships with brands have become more transactional," she said.

"That emotional connection between brand and consumer is weakening," she said. "They don't need to rely on (brands) so heavily for inspiration and resources. They have 2,500 bloggers and a variety of social networks telling them what to do."

Online browsing = online sales?