I closed out last week's column with the assertion that the most notable brands of the past 20 years or so - Amazon, Krispy Kreme, Microsoft, Southwest Airlines, Starbucks - have been built not by TV advertising, but by PR. It's an assertion that requires some clarification, as well as a long, hard look at how we define (and practice) PR.First, it's probably fair to say that most of those companies didn't rely on traditional public relations any more than they relied on advertising. Sure, Southwest Airlines has demonstrated a mastery of the publicity stunt unrivaled in modern corporate America, dressing pilots up like Dracula on Halloween and having the company's CEO arm-wrestle one of his counterparts over an advertising slogan. And yes, Krispy Kreme has mastered the art of persuading reporters to turn out en masse to cover new store openings. But none of these companies has built its brand through good old-fashioned product publicity. They achieved their current success by practicing what I've started calling "DNA Branding." A quick Google search found no matches for the phrase, so I guess that affords me the right to define it. DNA Branding is the process of building a brand from the inside out, of starting with a clearly defined vision; using that vision to create a distinct corporate culture; and then fashioning a brand that's an extension of that culture. Most advertising people - and most of the marketers to whom they report - seem to believe a company's brand is defined by what it says about itself. But practitioners of DNA Branding understand that their brands are defined not just by what they say, or even by what they do, but by who they are. Their brand personality is rooted in the DNA of the organization. Southwest Airlines is a DNA Brand. The things that make it stand out from other airlines - its humane work environment, its sense of fun, its quirky sense of humor - are embedded in its culture. There is nothing false or forced about them. (One of my favorite stories involves another airline that attempted to replicate Southwest's success by having a pilot dress up in fancy dress to attract media coverage. The pilot, on a new route into Miami, dressed up as Fidel Castro. Cuban-American passengers were not amused.) It should be apparent from this that DNA Branding is hard work. It can't be achieved with a snappy slogan and a catchy jingle. And it can't be manufactured by advertising people or traditional PR approaches. But PR is uniquely well-placed to lead the DNA Branding process because PR is a multi-stakeholder discipline (DNA Branding begins with employees) and because DNA Branding is all about building relationships. Paul Holmes has spent the past 16 years writing about the PR business for publications including PRWeek, Inside PR, and Reputation Management. He is currently president of The Holmes Group and editor of www.holmesreport.com.