PORTLAND, Maine — Just this week, Best Buy said it would lay off 2,400 employees as it struggled to compete with online retailing. That follows the bankruptcy and eventual liquidation of large retail chain Borders, whose demise also was blamed largely on pressures from online enterprises.

Those companies aren’t alone; the retail past is littered with names such as Zayres, Circuit City, LaVerdiere’s and others that had a time and now are gone, for a variety of reasons.

Retail is ever-changing, but technology is changing the pace of those changes, in many cases allowing consumers to change their behaviors in ways that leave many traditional businesses behind.

“It’s a great time and opportunity for us all, and also a time of challenges for brick and mortar retailers,” said David Stone, co-founder and CEO of CashStar, a Portland business that is a leading innovator in e-gift card systems.

The importance of innovation and the shifting business landscape were dominant themes at CashStar’s second annual “Digital Gifting Retailer Roundtable,” held Thursday at the Ocean Gateway terminal. The day featured talks by analysts and leading thinkers in areas including marketing and e-retail, with an audience of about 200 executives and e-commerce experts from companies ranging from L.L. Bean to The Home Depot.

Former Gov. Angus King, who is running for U.S. Senate as an unenrolled candidate, started off the day with a brief talk about innovation. He talked about Hussey Seating, a North Berwick company founded in 1835 to make farming plows. The company changed over the years, and today is a global leader in producing seating for stadiums.

“What if they had stuck to making plows? They’d be gone,” said King. “If you don’t innovate in this world, you’re going to be dead.”

Technology has changed the world dramatically, said King, who stressed that the Internet, in particular, has caused the “repeal of geography.” That helps a state such as Maine, which is geographically disadvantaged, he said. He noted a ski shop in Jay that, through a website, sold high-end racing skis to customers around the world.

“Because of the Internet, the barriers to entry are lower. You can start with an idea,” he said.

Sunil Gupta, a professor of marketing at Harvard University, remarked on the amazing technology innovations that currently exist, from digestible computer chips that send digestion data to doctors via cellphone communications to 3-D printers that can create prosthetic jaws. The question, he said, is whether consumers are changing to adopt new technologies.

He mentioned different technology innovations, and how long it took for them to hit 150 million users or units produced. The telephone took 89 years to get to 150 million users, he said. TV took 38 years, and the cellphone took 14 years. It took the iPod seven years, and five years for Facebook to hit 150 million users.

The rate of adoption is increasing. And that has implications for businesses large and small. One of the big current and growing trends is the use of mobile technology, largely smartphones and tablets.

When people are using mobile technology, 82 percent of the time they’re on applications — they’re not Web browsing, said Gupta. So for businesses, the question is how to get an app people will want on the devices, he said.

There are different answers. One, a basic one, is to add a unique value through an app, such as Starbucks using mobile technology to host e-cards. Another is to tap into a social strategy, using the company’s marketing to facilitate friends interacting with each other. An example is a jogger’s application that shares a runner’s efforts on social media, allowing others to cheer them on from another device or computer, remotely.