Bram Cohen, the mastermind behind BitTorrent, claims he didn’t set out to build a pirate ship when he launched the file-sharing product in 2003. All he wanted to do was make it easier to move big stuff around the web—video­game updates, maybe, or the Linux distros that developers liked to swap. But within a year of starting the company, files shared on BitTorrent made up more than a third of all traffic on the internet. While Netflix was still stuck in the mail-order business, BitTorrent was changing how and why we watch things online.

At first, Cohen was simply solving a puzzle: There was this logistical problem of how to move large files around, he says. “I figured out how to make it happen.” Unlike other peer-to-peer platforms, where downloaders had to rely on one person’s computer and their sharing largesse to access a file—remember Napster?—BitTorrent divided the uploading work among the masses, with each “seed” computer providing only a small part of the total file. Suddenly files moved faster, and uploaders could share files without killing their bandwidth or raising eyebrows at Comcast.

Many early BitTorrent users had perfectly legit and legal goals, like the Phishheads and Deadheads who grabbed entire concerts with the bands’ blessings. But shaky, low-res versions of summer blockbusters and Must See TV soon started flying around the web, and Cohen’s tech became synonymous with the illegal-download industry. Didn’t want to pay for a new movie? Torrent it. Missed last week’s episode? It’s already up on KickassTorrents. Hollywood executives, who had been spared the existential threat of Napster only because video files are much bigger and more annoying to transmit than music files, saw their own bogeyman approaching.

The execs sicced their lawyers on BitTorrent users, hoping to sue the pirates into oblivion. In 2012, industry lobbyists even pushed for a bill called the Stop Online Piracy Act, which would have let the government essentially shut down any website hosting pirated content. But these efforts failed, in part because “breaking big files into smaller, more distributed pieces and tracking their assembly” is not itself illegal, and BitTorrent Inc. couldn’t be held responsible for how its platform was being used. BitTorrent survived the worst that Hollywood could throw at it, and Hollywood realized it couldn’t stop anyone from torrenting—it could only hope to learn from those who had come before.

The music industry had concluded in the early aughts that the only way to compete with free is better. So just as record companies worked with Apple et al. to sell high-quality audio files free of the glitches and viruses that marred so much Napster content, entertainment executives countered BitTorrent by creating or partnering with platforms where people could pay for crisp, trouble-free HD video. Netflix, Hulu, and Amazon Prime Video all owe at least part of their existence to BitTorrent and its messy, malware-lousy downloads.

Piracy remains a massively popular global pastime—BitTorrent Inc. tells potential advertisers it has 170 million users per month. And entertainment execs have more or less made peace with its inevitability: When top brass at HBO see that Game of Thrones is the internet’s most pirated show, they wear the distinction like a badge of honor (while sending out perfunctory cease-and-desist letters). Then they make sure HBO Go’s back-end streaming tech serves up dragons that are brighter, sharper, and more terrifying than anything you could see for free.

Fast broadband and cheap server space largely have rendered Cohen’s original problem irrelevant, and most users have plenty of legal ways to download or stream video. But BitTorrent continues to shape how we think about storing and moving big things around the web. It’s easy to draw a straight line between BitTorrent’s decentralization of file-sharing and today’s blockchain-based cryptocurrencies—different technologies trying to spread control so wide that no single entity can break the system. Meanwhile, BitTorrent and its fellow pirate ships still loom as quality-control phantoms, hovering over the entertainment world and reminding those in charge what’ll happen if they stop doing right by viewers. Free content is just a download away.

David Pierce (@­pierce) wrote about augmented-reality workspaces in the February issue.

This article appears in the March issue. Subscribe now.