Peer-to-peer

Peer-to-Peer (P2P)

Peer-to-peer (P2P) is a decentralized network architecture in which each participant (called a peer) can act as both a client and a server. In a P2P network, peers share resources directly with one another without the need for a central server or authority.

P2P networks are commonly used for file sharing, blockchain applications, distributed computing, and communication platforms.

How It Works

In a peer-to-peer network, each peer is both a consumer and a provider of resources. Instead of sending requests to a centralized server, peers exchange data directly with other peers.

Key features of P2P networks include:

• Decentralization – No central control point
• Scalability – The network grows as more peers join
• Resource sharing – Bandwidth, storage, and computing power are shared
• Redundancy – Data is often distributed across multiple nodes

There are two main types of P2P networks:

• Unstructured P2P – Peers are connected randomly. Examples: Gnutella, Kazaa
• Structured P2P – Peers use a defined protocol to maintain an organized topology. Example: BitTorrent, Distributed Hash Table (DHT)

Applications of P2P

• File sharing – e.g., BitTorrent, eDonkey, Gnutella
• Cryptocurrencies – e.g., Bitcoin, Ethereum, which use P2P to maintain distributed ledgers
• VoIP and messaging – e.g., Skype (early versions), Tox
• Distributed computing – e.g., SETI@home, Folding@home
• Content delivery – e.g., IPFS (InterPlanetary File System)

Advantages

• High fault tolerance – The network continues operating even if multiple peers go offline
• Load balancing – No single server is overwhelmed with traffic
• Resilience and redundancy – Files and services are often duplicated across many peers
• Scalability – Performance improves as more peers join and contribute resources

Disadvantages

• Security risks – Peers may distribute malicious content or expose personal data
• Inconsistent performance – Resource availability depends on peer participation
• Legal concerns – P2P is often used for unauthorized file sharing
• Difficult management – Lack of central control makes enforcing rules or updates challenging

P2P vs Client-Server Architecture

In client-server models, clients request data or services from a centralized server. In contrast, P2P networks eliminate the server, with each node communicating directly.

Feature	Client-Server	Peer-to-Peer
Central server required	Yes	No	Scalability	Limited by server capacity	Increases with more peers	Single point of failure	Yes	No	Resource distribution	Centralized	Distributed	Examples	Web hosting, email	BitTorrent, Bitcoin

Legal and Ethical Use

P2P technologies are neutral and can be used for both legitimate and illegal purposes. Many open-source projects, content creators, and research institutions use P2P to distribute data efficiently and reduce hosting costs.

See Also

• BitTorrent
• File sharing
• Distributed computing
• Blockchain