Correction: An earlier version of this story inaccurately said that downloads of podcasts through iTunes reached 1 billion last year. Subscriptions of podcasts, not downloads, reached 1 billion. The story has been corrected.

This American Life executive producer Alex Blumberg, left, who's starting his own for-profit podcast business, and co-founder Matt Lieber, pose for a portrait in their office building in Brooklyn, NY, on September 10, 2014. (Yana Paskova/For The Washington Post)

They were too clunky to download. The topics were sometimes a little too obscure. And they didn’t really make any money.

Podcasts, the short-form audio files that entered the mainstream with the original Apple iPod, have been around for more than a decade. But while Apple this year discontinued the classic version of its iconic device, the podcast is resurgent, drawing hard-core fans who want to listen to other people talk about, well, pretty much everything.

An average of 1.5 million listeners a month download “99% Invisible,” a program produced on a shoestring on the theme of design. Sports are such a popular topic that when ESPN suspended Bill Simmons for his podcast tirade against NFL Commissioner Roger Goodell, fans of his “B.S. Report” helped make #FreeSimmons a top trending term on Twitter. A new series from “This American Life” producer Alex Blumberg — about starting a podcast business — has quickly become one of the top 10 most-downloaded programs in the country.

And, importantly, podcasts are finally profitable.

“It’s sort of a renaissance. Podcasts are in vogue,” said Todd Cochrane, chief executive of RawVoice, a podcast data research firm.

Maybe it’s the intimacy of hearing soothing voices piped into your ears through a pair of headphones — or maybe it’s just how much time people need to kill listening to something. Americans spend more than three hours a day commuting, working out and doing household chores that can be accompanied by audio entertainment, according to census data studied by Matt Lieber, a former public radio producer who co-founded the podcast company with Blumberg.

Smartphones and Bluetooth-enabled cars have made it easier than ever for listeners — who are still mostly men — to load up their favorite programs. And instead of the old way of downloading them from iTunes onto a computer and syncing with an iPod, listeners can grab shows straight from the Internet onto their smartphones.

Last year, Apple said subscriptions of podcasts through iTunes reached 1 billion. RawVoice, which tracks 20,000 shows, said the number of unique monthly podcast listeners has tripled to 75 million from 25 million five years ago.

And the connection that people can feel toward their favorite podcasts is exactly the sort of relationship that many media companies are trying to build with their users. At a time when people can easily skip TV ads, messages from sponsors on podcasts have a way of sinking in, especially when they’re read by the hosts of the show themselves, analysts say. As a result, this second wave of podcasts — unlike the first go-round — is promising to make more money.

“Five years ago, podcasting was very much a hobbyist’s activity and many people weren’t making them to make money,” said Tom Webster, a vice president of strategy at polling firm Edison Research. “But audience sizes have grown consistently, and each listener is listening to more shows as part of their weekly habit. That’s brought major producers to embrace podcasting.”

When Roman Mars began his quirky public radio show on the topic of design, he never expected it to amount to much.

The show “99% Invisible” was small in every way. Each episode ran for just 4 minutes 30 seconds, short enough to wedge between segments of big shows like NPR’s “Morning Edition.” It was esoteric, with back stories on the way the periodic table and parking meters were designed. Mars had a tiny budget of $5,000 and wrote, narrated and produced the show from the bedroom of his Oakland, Calif., home.

The show was warmly received when it started airing four years ago on San Francisco’s KALW. But off the airwaves — in the world of podcasts — the show was a blockbuster. It is now consistently in the 20 most-downloaded podcasts on iTunes.

Mars quit his old public radio job and now works full time on “99% Invisible,” funded entirely by the show’s fans and a handful of sponsors. The show is still broadcast on a few public radio stations, but that “distribution means less and less over time,” Mars said in a recent phone interview from Dublin, where he was putting on a live show for European fans. “They have a great reach and I’m a huge fan of NPR, but right now, if I’m able to reach my audience directly through podcasts, the writing is on the wall.”

Despite some early enthusiasm, podcasts faded in popularity in the early 2000s, partly because of the many steps required to download them and play them in a vehicle. The introduction of the iPhone in 2007 changed that, making podcasts as convenient to access as a Netflix show. It’s easier to play them in cars, too, as automakers build wireless media functions into more and more models. And faster WiFi and mobile data speeds have made podcasts a snap to stream.

Radio is still far more popular and lucrative than the fledgling world of podcasts. The industry has withstood the disruption that the Internet wrought on newspapers and TV, partly thanks to an enormous audience of commuters trapped in cars. But podcast enthusiasts believe preferences are beginning to change.

“This is where radio syndication was 30 years ago, and this is just the beginning,” said industry veteran Norm Pattiz, chief executive of celebrity podcast channel PodcastOne. “What Netflix did for video is what podcasts are doing for radio today.”

Podcasters also like the personal connection they have with fans who listen through ear buds or headphones, which can make shows feel more intimate than other forms of media.

Mars said he keeps that in mind and mikes himself more closely than he used to. This allows him to use a quieter voice, which he calls a “head voice,” in the hopes of more closely connecting with listeners.

“My connection to the audience is something I completely cherish and is part of that medium that is really unique,” he said.

The flexibility of podcasts appeals to radio industry veterans whose shows have been dictated by rigid time blocks and long-held industry rules. Mars’s shows are now 20 minutes in length, allowing for deeper reporting and developed story lines. “Longform,” a podcast that interviews authors and magazine writers, runs much longer — too long to get picked up by any radio stations.

Even with the rise of six-

second Vine videos and viral listicles on the Web, Mars believes there is a strong appetite for long-form audio storytelling. It’s what keeps listeners committed for 20 minutes to stories about, for instance, Ikea hackers — people who mix and match Ikea furniture as a hobby.

Fans are so devoted that they have helped to raise nearly $600,000 in the past three years — money that has allowed Mars to hire three reporters and producers.

The money for podcasts is coming from not just fans but advertisers, too.

Pattiz at PodcastOne, a company that hosts and distributes podcasts, says his company sells millions of dollars of ads for popular podcasts by pro wrestler “Stone Cold” Steve Austin, talk host Adam Carolla and sportscaster Dan Patrick.

A new podcast launched in June starring Nicole “Snooki” Polizzi from the reality show “Jersey Shore” averages 1.5 million downloads per episode. Pattiz is scouting for more stars to launch podcasts. He has signed former CNN host Larry King and his wife, Shawn, and “Pawn Stars” host Rick Harrison.

The new podcast audiences inspired Blumberg, a former producer for NPR’s “Planet Money” program, to create a for-profit podcast company with narrative storytelling on a range of topics.

And he’s starting by reporting on himself and his new venture.

In the first three episodes of the series called “Startup,” Blumberg goes to Silicon Valley to meet with one of Twitter’s original investors, Chris Sacca, to pitch his idea. Blumberg invites listeners to eavesdrop on the investment conversations, where he initially falls flat explaining how the idea will become as successful as Twitter.

Blumberg and Lieber launched the show three weeks ago, and the first three episodes have jumped to the top five podcasts of the iTunes chart.

They are operating out of a shared office space in Brooklyn but have plans to build a production space.

“It was just so straightforward and totally not about begging to please buy this or that to keep the lights on,” Blumberg said. “It was pure excitement to realize if you have something people want, they are willing to buy it. That’s what these podcasts will generate.”