Daemon

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更新済 Jul 6, 2026

What Is Daemon?

A daemon is a computer program that runs continuously in the background, waiting for a specific event or condition before it becomes active. Rather than being started and controlled directly by a user, a daemon typically launches when a system boots and keeps running quietly until it is needed. The term is most common in Unix and Linux environments, where the names of such programs often end in the letter "d," for example, httpd for a web server or sshd for secure shell access.

In the context of cryptocurrencies, a daemon is the background software that allows a node to stay connected to a network, process incoming data, and respond to requests without manual intervention.

How a Daemon Works

A daemon spends most of its time idle, listening for triggers. These triggers can include a network message, a scheduled time, a hardware signal, or a request from another program. When the relevant condition is met, the daemon performs its task and then returns to a waiting state. This event-driven design lets a single program handle many requests over a long period while using minimal resources when nothing is happening.

Because daemons run without a direct user interface, they are usually managed through configuration files, command-line tools, or system services. A practical example is the software that keeps a Bitcoin node online: it runs in the background, validates transactions and blocks as they arrive, and communicates with other participants automatically.

Daemons in Blockchain Networks

Many blockchain clients are designed to operate as daemons. For example, the reference client Bitcoin Core includes a program called bitcoind (the "d" again indicating a daemon). It runs continuously to maintain a full node, meaning it stores a copy of the ledger, relays transactions, and helps enforce the network rules.

Running a client as a daemon is what allows a blockchain network to stay available around the clock. Each participating computer can keep its software active without a person watching over it, which helps the network remain decentralized and resilient. If you want to explore the different roles these background programs can play, you can read more about how nodes operate and why they matter.

In short, a daemon is a quiet but essential building block. It may not be visible to everyday users, but background processes like these keep servers, applications, and blockchain networks running continuously.

Learn more: What Are Nodes?

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