Few pieces of software have shaped the modern internet — for better and worse — as much as BitTorrent. Created by a single programmer in 2001, it solved a genuine technical problem so well that it became both a backbone of legitimate distribution and a byword for online piracy. Its story is a microcosm of the internet itself: ingenious, unruly and impossible to fully control.
An elegant idea
The problem BitTorrent set out to solve was simple: moving big files was slow and fragile. Traditionally, everyone downloaded from a single server, which buckled under demand. The programmer Bram Cohen, who released BitTorrent in 2001, turned that model inside out.
Instead of pulling a file from one place, a BitTorrent user joins a "swarm" of other users and downloads small pieces of the file from many of them at once — while simultaneously uploading pieces they already have to others. The counterintuitive result is that the more people want a file, the faster it can spread, because every downloader also becomes a source. It made distributing huge files cheap and efficient, without a costly central server.
Fame — and infamy
That efficiency had an obvious appeal for sharing large media files, and BitTorrent quickly became strongly associated with copyright infringement. The technology itself is neutral — it moves any file, legal or not — but it soon underpinned a vast ecosystem of "torrent" sites offering pirated films, music, games and software.
The response from rights holders was fierce. The music and film industries pursued waves of lawsuits and takedowns, and high-profile torrent sites — most famously The Pirate Bay — became the target of prosecutions and shutdowns around the world. Yet the technology's distributed nature made it resilient: as one site closed, others appeared, and the underlying protocol carried on.
Alongside the piracy, BitTorrent had entirely legitimate uses that continue today. Makers of free operating systems such as Linux distribute their large installation files by torrent; game companies have used it to push out updates and patches; and researchers and archivists rely on it to move enormous datasets. For those uses, its efficiency remains genuinely valuable.
The company behind the protocol
To try to commercialize the technology, Cohen and a co-founder set up BitTorrent, Inc. in the mid-2000s. The company brought a popular, lightweight client, µTorrent, under its wing and experimented with legitimate products. At its height, BitTorrent's software was used by hundreds of millions of people, and the protocol at times accounted for a large share of all internet traffic.
Turning that reach into a stable business, though, proved hard — not least because the technology's most enthusiastic users were often those least inclined to pay for anything.
The crypto turn
In 2018, BitTorrent took an unexpected turn. The company was acquired by Justin Sun, the entrepreneur behind the Tron blockchain, in a deal reported to be worth around $140 million. The following year, the network launched a cryptocurrency token, BTT, designed to reward users who share files by keeping them available to others.
The pivot tied a two-decade-old piece of internet plumbing to the volatile world of crypto — and to its controversies. Sun and his ventures later drew regulatory scrutiny in the United States over their token sales, and the business that had grown up around BitTorrent was restructured and renamed. Cohen, the protocol's creator, had moved on to other projects.
An enduring legacy
More than 20 years on, BitTorrent endures as one of the internet's most polarizing creations: admired by engineers and open-source advocates for its elegance, condemned by the entertainment industry for enabling piracy, and, latterly, entangled in cryptocurrency. It is a reminder that a powerful technology, once released, takes on a life its creator can neither fully predict nor control — and that the same idea can be, at once, celebrated and reviled.
