Perusohjelmiston

Perusohjelmiston, literally “base software” in Finnish, refers to the set of software that forms the foundation for a computer system or device to operate, distinct from end-user applications. It includes the core components that enable the system to function, such as the operating system, system libraries, and basic utilities, as well as the drivers that allow hardware to be controlled and used effectively.

The scope of perusohjelmiston can vary by platform. Desktop and server environments rely on an operating system along with kernel modules, drivers, and standard system tools. Mobile platforms like Android and iOS also include a base layer that enables apps to run and access hardware features. In embedded systems, the base software tends to be smaller and highly specialized but remains essential for reliability and hardware control.

Perusohjelmiston is distinct from application software, which provides user-facing tasks like word processing, media playback, or games. Nevertheless, the base layer exposes interfaces and services—such as application programming interfaces and runtime libraries—that applications use. Updates to the base software are critical for security, compatibility, and performance, and are typically delivered through device firmware or OS update mechanisms and software repositories.

In practice, organizations and manufacturers consider perusohjelmiston when evaluating security posture, maintainability, and total cost of ownership, including license terms and support. Some ecosystems favor a minimal base software with optional components, while others deliver more feature-rich base environments to support a wide range of applications and use cases.