firmware

Firmware is a specialized class of software that provides low-level control for a device's specific hardware. Stored in non-volatile memory such as flash ROM or EEPROM, it is executed when the device powers up and remains intact between sessions. Unlike general-purpose software, firmware is tightly coupled to the hardware design and implements the fundamental routines that initialize components, manage basic I/O, and expose a stable interface for higher-level software.

Firmware sits between hardware and higher-level software, forming a bridge that enables hardware features to be used by applications. It can be updated to fix bugs, add features, or patch security vulnerabilities. Many devices include a bootloader that can reflash the main firmware image, often with cryptographic signing and mechanisms to prevent or recover from failed updates.

Examples include BIOS or UEFI firmware in personal computers, router firmware, printer firmware, and embedded firmware in consumer electronics such as cameras, smartphones, embedded medical devices, and automotive control units.

Update methods vary by device. Desktop and laptop firmware updates are distributed by manufacturers through dedicated utilities; embedded devices may receive over-the-air updates or be updated via a service interface. Updates typically require checksums or digital signatures and may include rollback or recovery modes to prevent bricking.

Security and reliability considerations are central to firmware management. Because firmware runs with high privileges, tampering or insecure updates can compromise devices. Practices include secure boot, code signing, trusted update channels, and integrity verification, as well as careful supply-chain management and version control.