offline

Offline describes a condition in which a device, system, or service operates without a connection to a network or the internet. In everyday use, many software applications can run in either offline or online mode. The term contrasts with online or connected states, where data and services are accessed remotely.

In computing, offline capabilities are designed to preserve functionality when connectivity is unavailable. They rely on local storage of information, caches, or embedded databases so users can continue work without a network. When connectivity is restored, data can be synchronized with remote servers.

Technologies enabling offline use include local databases, file-based storage, and caching strategies. Progressive web apps and service workers enable offline web experiences by prefetching assets and intercepting network requests. Mobile apps frequently implement an offline mode for field work, travel, or intermittent access.

Common applications include document editing without internet, offline maps, downloaded media for offline viewing, and enterprise tools used in remote locations. Offline operation helps preserve access to information and can reduce bandwidth usage during peak network demand.

Challenges involve data reconciliation after offline periods, conflicts from concurrent edits, storage limits on devices, and ensuring security and privacy for locally stored data.

Designing effective offline systems emphasizes graceful degradation, synchronization strategies, and user experience that remains useful despite connectivity gaps.

See also offline-first, progressive web apps, synchronization.