This week’s “Daily Journal” guest columnist is Kristen Blair, N.C. Education Alliance Fellow.

RALEIGH — For scores of aspiring college-bound 12th-graders, an epic era of nail-biting has begun. Early January, synonymous with admissions deadlines at many undergraduate institutions, marks the end of the application process and the advent of the interminable wait.

Packed with hope, hard work, and careful messaging, students’ applications now must withstand the judicious scrutiny of college admissions officers. As colleges weigh students’ academic lives on a balance, what matters most?

The constants of a college application — a student’s GPA, test scores, personal essay, and letters of recommendation — still reign supreme. But schools increasingly are throwing an unofficial, contemporary component into the mix: the digital dossier.

Over the past three years, the percentage of college admissions officers who mine social media for student information has more than doubled, according to Kaplan Test Prep. Kaplan’s latest survey of admissions officers from the country’s most competitive colleges and universities found that 24 percent have checked applicants’ social networking pages. Online appraisals aren’t limited to social sites; 20 percent of admissions officers have Googled applicants as well.

Most of what they’re finding isn’t decimating dreams. But some is: 12 percent of admissions officers have uncovered behavior that affected student eligibility negatively. Such offenses, according to Kaplan, “included essay plagiarism, vulgarities in blogs, alcohol consumption in photos, and ‘illegal activities.’”

Today’s teens ought to take notice. After all, 95 percent of 12- to 17-year-olds are online, the Pew Internet Project found; 80 percent use social networking sites (with one survey showing 20 million kids under 18 just on Facebook). Kids are generating copious content, some of which may come back to haunt those who overshare.

Online searches by admissions officers are not “routine” — yet. But Kaplan’s vice president of research, Jeff Olson, points to “a growing acceptance by college admissions officers” of vetting applicants online. He advises college applicants “to be particularly mindful of what they post” and suggests they “search online to make sure their digital footprint is clean.”

That’s sage advice. But kids ought to safeguard their digital reputations long before college applications roll around. Both middle and high schools should educate students and parents about the impact, accessibility, and longevity of material posted online.

Most provide some guidance: 70 percent of online teens have received advice about Internet safety from school personnel, according to Pew; 86 percent have heard from parents about online safety and responsibility. In addition to verbal advice, younger teens need parental monitoring when they’re online.

Postponing Facebook until high school is also wise: Younger middle schoolers are much less likely than older teens to contemplate the long-range ramifications of what they post, Pew found. Moreover, many middle schoolers shouldn’t be on Facebook in the first place, since the site requires users to be 13 to comply with federal privacy law. Lying about one’s age violates Facebook’s terms of service and can circumvent the site’s protections for minors.

What about privacy? Survey data show about two-thirds of social networking teens use privacy settings to restrict their viewing audience. That’s sensible, but such settings aren’t bulletproof.

Content kids post online can be copied andpasted elsewhere. And security breaches can render the private, public. Witness the recent exposure of Facebook CEO Mark Zuckerberg’s personal photos.

Finally, privacy promises aren’t always kept. Facebook just settled Federal Trade Commission charges that it “deceived consumers” and repeatedly violated users’ privacy; Google settled an FTC privacy complaint in 2011 regarding Buzz, its early attempt at social networking.

What’s the bottom line for teens? Be careful online. And don’t forget that digital dossier. Others surely won’t.