Anyone who lived through the golden age of file sharing tends to associate P2P with one very specific function: downloading. Yet IETF’s RFC 5694 reminds us of something important: peer to peer enables many different applications, not a single category. Every time decentralizing solves a problem — cost, trust, resilience, censorship — P2P comes back, even under another name.
Peer to peer in digital content
Distributing a large file to a large audience is expensive. The traditional solution is a CDN: caches close to the user. The P2P solution is to make users themselves participate in distribution: BitTorrent remains the classic reference. It’s used by projects that need to distribute Linux distros, Wikipedia dumps, Internet Archive backups, game clients.
The structural advantage is that the more people want a piece of content, the more distribution scales. In the centralized world a spike in requests is a threat; in the P2P world it is a help.
Peer to peer in payments
Bitcoin, in the 2008 white paper, is defined as "a purely peer-to-peer version of electronic cash". P2P here is not about files but about value: a transaction is propagated among nodes, validated according to shared rules, recorded in a public common ledger. There is no central authorization server.
A whole ecosystem grew around this insight: Lightning Network for fast off-chain payments, other blockchains with different models, non-custodial wallets that talk directly to the network without an intermediary. Native digital money is, by design, P2P.
Peer to peer in storage
Projects like IPFS propose a way of referencing content based on hashes, not on URLs of a server. A file does not "live" in one place: it lives wherever someone replicates it. Ask for the hash, the network brings the pieces.
It’s the same scheme we learned from torrents, extended to the web: addressing by content, not by location. The result is a network where a site does not vanish just because the original server is off — provided someone has replicated the content. This kind of resilience has very concrete applications: cultural archives, technical documentation, materials that want to outlive their authors.
Peer to peer in civic and mesh networks
In contexts where the traditional network is scarce, censored or too expensive, community mesh networks have emerged: nodes that talk directly to each other without going through a commercial provider. They are P2P at both physical and logical level. There are historical experiments, civic projects, initiatives born after natural disasters to keep local communications alive even with compromised infrastructure.
The pattern repeats: when the center fails, a network of peers can fill the gap. Not always as well as a professional infrastructure, but sometimes it’s the only option available.
Peer to peer in communications
Messaging too has its P2P story. Many modern systems are formally centralized (the server acts as a relay) but use end-to-end encryption, which in practice turns the server into a pure forwarder of encrypted packets. More radical projects experimented with direct P2P transport, serverless, with all the pros and cons — discoverability, NAT, availability.
Peer to peer in open source collaboration
Git, the tool that supports the entire software industry, is P2P in model. Every clone is a complete repository with the full history. GitHub and the like added a "social" center for practical purposes — issues, pull requests, permissions — but the technical core remains a distributed graph of equivalent copies. You can synchronize two repositories without any server.
P2P appears every time a community wants to remove an intermediary: from content to money, from storage to knowledge.
Peer to peer as social, not just technical, logic
The thread connecting these examples is subtle but strong: in each one, the choice to "remove the center" is not just an optimization. It’s an answer to a question: whom do we trust? Trust does not disappear when you decentralize; it moves. From the operator of a service to a protocol, to a consensus algorithm, to a cryptographic signature, to a community. The job of modern P2P is to choose well where to place it.