This show debuted 20 years ago. We never watched TV the same again.

Twenty years ago, Jack Shephard opened his eyes, and television was never the same.
ABC aired among the most instantly compelling television pilots of all time, the first episode of the groundbreaking drama “Lost,” on Sept. 22, 2004. For six seasons, it provided one of the great shared TV experiences — and previewed the way we would consume television for the next two decades.
There was a time when watching TV was a far more isolated experience, and you could feel like you were the only person in the world who was such a fan of your favorite series. But these days, watching a show and then listening to podcasts, reading recaps and browsing subreddits picking the episode apart is simply how we consume it. While certain aspects of that ritual existed before 2004, “Lost” played a significant role in cementing this process of consumption for the mainstream viewer.
For a series with such an impact, its origins were humble: ABC executive Lloyd Braun envisioned “Lost” as essentially a TV version of “Cast Away.” But co-creators J.J. Abrams and Damon Lindelof had grander ambitions. The pilot expertly hooked audiences by presenting not just one central mystery, but tons of them, establishing what the series would continue. What is the monster in the jungle? Why is there a polar bear on a tropical island? Why has a distress call from a French woman been repeating for 16 years?
As the show progressed, the dizzying number of questions asked of the viewer made it a water cooler show unlike any before it. It was simply not possible to watch “Lost” without wanting to discuss and debate what was truly happening on the island — and what the island was in the first place. But compared to the time of earlier serialized mystery shows like “Twin Peaks,” a majority of Americans now had home computers, and the water cooler was expanding beyond your office and circle of friends to encompass the entire planet.
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Indeed, as significant to “Lost” as Sept, 22, 2004, is another date: June 28, 2005, the day Apple added podcasts to iTunes and made them far easier for millions of fans to download. Weeks earlier, “Lost” wrapped its first season with a juicy question that demanded to be talked about over the summer — what’s in the hatch? — and it became one of the first shows to spawn numerous weekly podcasts dedicated to recapping episodes and debating theories. Further, message boards devoted to specific shows were becoming more popular, and internet speeds were now fast enough to facilitate live episode discussions while the show was airing. For some viewers, this would be their introduction to the idea of a second-screen experience. 
“Lost” was clearly designed to feed into all of this with its tendency to throw out bits and pieces of information like breadcrumbs, from glimpses of a pair of skeletons to a shot of a strange four-toed statue and blink-and-you-miss it appearances by the numbers, as if to say, “Have fun analyzing this one, message boards!” The recent proliferation of DVR made it easier for Easter eggs — like a DHARMA logo appearing on a shark for a split second — to be spotted and spread like wildfire on forums, further fueling conspiracy theories.
The show thrived on interplay between the creators and fans online, including with one of the first official podcasts for a TV series, hosted by showrunners Damon Lindelof and Carlton Cuse. They were so in tune with fan theories, they would sometimes respond to them in the show itself. When some viewers thought a bird said Hurley’s name in Season 1, Hurley brought this up the following season. It was as if the fans trying to figure out “Lost” were another character in the show. 
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Taking this to the next level was the Lost Experience, an alternate reality game that unfolded between seasons. Fans were asked to decode clues through a website and phone number for a fake company, advertised during commercial breaks as if it were real. The experience even made its way into the real world when one of the game’s fictional characters crashed the “Lost” Comic-Con panel in 2006 to further the story. It wasn’t just a fun way to pass the time over the hiatus, as the game provided key information about the mysterious numbers that would never be revealed in the show. There was also exclusive content created for the internet, a series of canon “webisodes” dubbed “Missing Pieces” first made available on Verizon Wireless phones.
More than any series that came before, “Lost” was establishing that if you wanted the complete experience, you had to be online, as it extended far beyond the one-hour episodes.
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Since “Lost,” more shows have been written with the understanding that there will be an audience of fans ready to play along and unpack episodes. Look no further than Season 1 of “Westworld,” which was constructed like a puzzle box filled with clues for podcasters. Shows like “Severance” and “Yellowjackets” have followed in the “Lost” legacy in the way they thrive on slowly teasing out overarching mysteries. Head over to the dedicated subreddits for either show and you’ll find dozens of threads with theories and screenshots of Easter eggs that look just like the “Lost” forums of yore.
Whether the fan theory machine that “Lost” helped build is entirely positive is up for debate. The downside is it has become difficult to be truly surprised by TV in the post-“Lost” era of frenzied fan theorizing. The main twist of “Westworld” Season 1 was figured out weeks in advance and plastered all over Reddit in a way that almost qualified as a spoiler, and every “Game of Thrones” podcast had Jon Snow’s parentage solved for years. In a world where millions of viewers crowdsource theories and treat solving a show like a second job, almost any twist it can dole out has been proposed by someone at some point and is therefore less shocking when it happens.
Leaning into bait for fan theories can also backfire when the real solutions can’t possibly live up to the anticipation, hence the controversial nature of the final season of “Lost.” Playing along with solving the mystery was so much fun that some fans lost sight of the fact that at the end of the day, the heart of “Lost” was its characters. So when the finale was more about touching emotional beats than major reveals, it was polarizing.
But if “Lost” was fundamentally about damaged people being brought together to heal through one another, it’s appropriate that the show helped evolve the TV experience into a more communal one, reminding us of the joys of living, and watching, together.