– The age-old issue came up again recently: A potential client asked Nate Hartmann, “Hey, how old are you?”

Since Hartmann founded Yellow Box in 2010 at age 18, he has encountered skeptics who doubted his company could design websites and create online marketing strategies. Some clients even set out to teach them.

“They tried to run us instead of working with us to achieve their goals,” said Hartmann, whose company is based in Chicago.

Not being taken seriously is an obstacle many young entrepreneurs face. There are others, like being a boss without experience, or not understanding some legal and financial issues. But being young also has advantages. Though they may still have schoolwork to do, most owners don’t have responsibilities like families or mortgages to distract them. And they bring fresh eyes to creating products and services.

“I didn’t have preconceived notions, didn’t have any processes to shake,” Hartmann said. Many competitors worked at larger marketing firms, he says, and “do things that aren’t efficient. But that’s what they do because they did it at the last place.”

Nearly 545,000 companies owned by people under 25 were noted in the Census Bureau’s 2012 count of established businesses, the most recent statistics available. That was 2.4 percent of all the companies in the survey. But it’s certain that thousands of other young people, including those inspired by Facebook’s launch by a 19-year-old Mark Zuckerberg, have started businesses that weren’t counted or didn’t last long.

Although many parents support their entrepreneurial children, they can also be pessimists. Ryan Neman discovered that at age 19, when he and Skyler Lucci started HeyTutor, an online company that matches tutors with students.

“I got a lot of backlash from family and friends,” said Neman, based in Los Angeles. But he says, “I used the doubtfulness of other people to build a fire and prove them wrong.”

Neman’s father gave advice as he told his son to focus on school. But Neman dropped out of UCLA.

Neman was younger than many tutors he hired. “It’s hard to interview someone who looks significantly older than you,” he said. Clients who were parents would ask, “How much trust can I offer you if you’re so young?”

Five years later, having had success, he finds more acceptance.

Young entrepreneurs are ideal for coming up with products and services aimed at people in their 20s and 30s because they understand the market and how to use social media to reach customers, said Lakshmi Balachandra, an entrepreneurship professor at Babson. But she sees some students struggling when an older person offers a suggestion.

“They don’t necessarily want to hear advice or feedback, and that’s part of the challenges they face,” she said.

They can also ignore some important aspects of running a company. Taylor Toce started Velo IT Group, a technology services company, in 2006 at the age of 17. Toce said he was brave but ignorant; he was surprised by a lawsuit brought by a former staffer.

“You’re not thinking about legal matters and insurance and human resources — you’re thinking about producing income and helping clients,” Toce said. He settled the case, which helped him realize that his company needed an employee handbook that spelled out its policies.

Carl Dorvil was 20 and at Southern Methodist University when he started a tutoring service, Group Excellence.

“I didn’t know what I didn’t know,” said Dorvil, who recalls donating tablet computers to a school district, hoping that would lead to requests for tutors.

Dorvil, now 34, sold his first company, started another, GEX Management, and took it public in 2016. He’s glad he didn’t think too much 14 years ago about the challenges ahead.

“If I knew how hard it was and all the risks out there when I started, I probably would never have started,” he said.