Still, traditional Black Friday fans remain—those consumers who revel in getting up early for the sales at malls. As the holiday season starts, here’s a look at some of shopping’s generational trends.

THE ECOSHOPPER

Lylla Hinchcliff, an 18-year-old college freshman at Kent State University in Ohio, says a class focused on climate change triggered a change in her shopping habits over the past six months. “In the past, I didn’t put too much thought into what I was buying but ever since that I’m more eco-aware,” she said. “I just think, ‘Should I really be buying this?’ I now want to be able to support what companies stand for.”

A growing number of younger shoppers consider themselves environmentally conscious and want to shop accordingly, buying local or from brands that promote themselves as socially responsible, like the clothing company Everlane.

“More than other generations, younger consumers take a more active approach to researching and understanding brands’ corporate responsibility efforts,” says Diana Smith, associate director of retail and apparel research at Mintel. A recent Mintel survey showed 46% of millennials said they had supported a retailer because it was transparent about the way it produces what it sells; 43% of those younger than that, known as Generation Z, gave the same answer.

Labels from Gucci to fast-fashion retailer H&M are making efforts to appeal to these shoppers. “We do expect to see the socially and environmentally-conscious consumer trend grow and become an increasingly important factor in choosing one retailer over another,” says Jill Standish, senior managing director and head of consulting firm Accenture’s retail practice.

When it comes to gifts this year, “instead of thinking about the quantity of things I’m going to buy, I’m more thinking of quality,” Ms. Hinchcliff says. On Black Friday, she plans to look online for brands who align with her new outlook to check what sales they are promoting. She also plans to shop at retailers in her area, to be more sustainable. “I told my family you all are getting cool local gifts this year,” she said. “They’ll be excited to get things from an area they’ve never been to. It will be fresh to them.”

Many younger shoppers are also drawn to the rising number of secondhand sites. Korrinne Cannaverde, a 32-year-old bookkeeper in Blairsville, Ga., started shopping with online secondhand retailer thredUP last year after learning about it on YouTube. “I was first attracted to thredUP because of the discounted prices,” says Ms. Cannaverde, who has two small children. “But now, their vision of cutting back on waste for the planet has really revolutionized how I buy clothes not only for me but also for my family.”

For gifts, “I either try to buy things that are sustainable or ‘give back’ in some way,” she says.

The Profile

Prime age: 18 to 35

Philosophy: Buys from companies that are transparent about how and where their products are made, promote the environment and recycling, support causes.

Retailers & Labels: Everlane, Reformation, the RealReal, thredUP

THE ONLINE CONVERT

Hank Peña, a 49-year-old married father of two in Boston, last year for the first time shopped entirely online during the Black Friday weekend spanning Cyber Monday.

Before that, he made annual trips to the mall, scouring ads and heading out early Friday or, more recently, after Thanksgiving dinner—once lining up as part of an early-rush doorbuster crowd to snag an expensive television at a deep discount. Over the years he was turned off by reports of shoppers being trampled and the feeling the deals weren’t attractive enough to justify braving crowds in the wee hours.

“There are better sales online, and the sales are online more often,” says Mr. Peña, an exterminator and aspiring screenwriter who does most of his online shopping on Amazon. “There’s now nothing to incentivize me to go into a store,” he says. "It used to be fun. It used to be a big deal. But it’s lost its luster.”

Among Generation X, approximately ages 39-54, many of those who grew up with doorbuster traditions now are joining younger shoppers in shifting to online shopping. “They are the biggest converters,” said Marshal Cohen, chief industry adviser, retail, at NPD Group. 

In a survey this year, 58% of Gen X shoppers cited a preference for holiday shopping online, up from 43% in 2015, says Rod Sides, vice chairman and U.S. retail leader at Deloitte. “It’s the highest preference of any of the cohorts we have,” he added, referring to Gen X.

“It’s pretty telling that this generation has now transitioned essentially to online in terms of their preferred place to shop. This is not a digitally native group,” Mr. Sides said.

Intensifying the draw of online shopping for these holdouts is the emergence of websites and apps that focus on bargains, including DealNews, BFAds, ShopSavvy and The Coupons App.

The Profile

Prime age: Over 40

Philosophy: A recent devotee of online shopping after becoming disillusioned with the crowds and lackluster deals at in-store doorbuster sales.

Retailers & Apps: Amazon, department-store websites, ShopSavvy app

THE DOORBUSTERS

Darla Smith, 40, in Louisville, Ky., has been going shopping in stores for Black Friday sales since her son, William H. Smith, was 1 year old. Now 20, he joins her.

The two catch Black Friday sales at stores including Kohl’s, Target and Gamestop on Thanksgiving night, a few hours after their family dinner. They hit several stores from about 10 p.m. to 1 or 2 a.m. “Once I got old enough, I started just coming with her,” says Mr. Smith, a college sophomore. “My dad started to become really disenchanted with the whole thing. To me it was like new and interesting.”

Despite the rise of online shopping, some people still swear by Black Friday doorbuster deals at stores. Of the around 165 million consumers considering shopping over the five-day Thanksgiving weekend period, 47% said they would start their shopping in stores rather than online, according to the National Retail Federation and Prosper Insights & Analytics.

While some are older consumers who stick with longheld habits, perhaps surprisingly those under 25 were more likely than other age groups to say they expect to shop in stores. More than 80% of Generation Z responders in a Deloitte report released Monday said they plan to shop in stores during the holiday weekend.

“Even though they grew up with cellphones, they definitely like to go into the store,” says Lauren Bitar, head of the retail consulting practice at analytics firm RetailNext.

Darla Smith and her son have mapped out a strategy where he’s the designated line holder while she picks up more stuff. “We move through the line a lot quicker,” says Ms. Smith, who works in a hospital’s child-development center.

She scours print ads for deals, circling items she wants to buy and bringing the ads with her rather than using her cellphone. She still remembers the time she nabbed a $250 Dyson vacuum her mother-in-law wanted for $45 at an in-store Black Friday sale a decade ago. “It’s things like that that pull me in,” she says. “If I can get one big sale, then it’s definitely game on for me.”

Ms. Smith acknowledges the stores are always crowded, parking can be tough and that online shopping would be much easier. “But that’s so non-social,” she says. “I really like to get out there and see what it’s like.”

The mother and son see the Black Friday shopping spree as a chance to bond, especially since he’s now away at college. “I guess you can say it’s more now a tradition," Ms. Smith says. ”It’s just fun for the both of us.”

The Profile

Prime age: Spans generations

Philosophy: Enjoy the thrill of the chase for deals and the social aspect of joining other shoppers. For some, the outing is a holiday tradition.

Stores: Malls and shopping centers. J.C. Penney, Macy’s, electronics stores

Write to Ray A. Smith at ray.smith@wsj.com