WealthEngine sniffs out the rich.

The Bethesda-based firm combs through more than 50 types of public records, including databases of boat owners, airplane registrants, stock holders and property owners, to identify people who fall in upper income brackets.

In recent years, that’s become a more complex task. When chief executive Tony Glowacki joined the firm 12 year ago, WealthEngine had four million pieces of data to analyze. Today, that number tops five billion.

“We figured out how to take all this data that comes in tons of different forms and we normalized it for our use,” Glowacki said. “That’s what’s unique about what we’ve done.”

The arrival of big data and advanced computing have been transformative for technology firms that analyze reams of information to identify specific audiences that marketers want to purchase their products or services.

WealthEngine sells its findings to nonprofits in search of donors, financial service providers in search of clients or luxury brands in search of buyers. Often, WealthEngine’s data is used to augment data its clients are already collecting.

“When you go out externally and find data, you can add a ton more knowledge to the process,” Glowacki said. “When you create a model around that you can really begin to understand your clients in a much richer way.”

Marketers have long been mindful of where they run advertisements, selecting television shows or print publications based on the size and demographics of their audience.

The digital age has meant advertisers can access more information than ever before about how people spend their time, what products they buy, where they get their information and a host of other online habits.

“In the past the granularity of data was not that great,” said Kiran Hebbar, a general partner at Vienna-based Valhalla Partners. “What’s happened over the past few years is there is more and more data available from online sources and mobile sources.”

But Hebbar added that speed is also more important than ever before. Advertisers have a limited amount of time to identify a prospective buyer and capture their attention, which is more fragmented on the Internet than most other media.

“You need to make decisions in real time. When I consume media in an online mode ... within milliseconds the advertiser has to figure out if I’m the right consumer to target and if so what advertisement to target to me,” Hebbar said.

About 1.3 billion people share videos, news articles and other Internet content to their social networks each month using a widget created by McLean-based AddThis. The firm tracks every click.

But the company doesn’t just hoard the information. It’s used to help publishers and advertisers gain insight into which of their content is most popular among their desired audience and how they can turn that audience into customers.

“Isn’t that what advertising is about? It’s about the potential of generating action,” chief executive Ramsey McGrory said. “It’s about putting an offer in front of somebody, based on what you believe is the target audience, to generate the action you want.”

But McGrory said digital advertising, even if it’s geared toward a specific group, has been adopted slowly because marketers are accustomed to other forms of advertising, such as television, where the metrics of success have been defined over time.

“The reality is there has been so much money spent and analysis done that dependability of the old tried and true way of media buying still gives advertisers the scale and some idea of what the [return on investment] is going to be,” McGrory said.