Firmware is programming that's written to a hardware device's nonvolatile memory. Nonvolatile memory is a form of static random access memory whose contents are saved when a hardware device is turned off or loses its external power source.
Firmware, which is added at the time of manufacturing, is used to run user programs on the device and can be thought of as the software that allows hardware to run. Hardware makers use embedded firmware to control the functions of various hardware devices and systems, much like a computer’s operating system (OS) controls the function of software applications. Firmware may be written into read-only memory (ROM), erasable programmable read-only memory (EPROM) or flash memory. Firmware that is embedded in flash memory chips can be updated easier than firmware written to ROM or EPROM, which makes it more adaptable.
Today, embedded firmware exists in everything from smartphones to internet of things (IoT) devices that are so simple you might not imagine they had computer control. While the firmware in a smart light bulb may not need frequent updates, the firmware on a smart thermostat may need to be updated periodically to remain compatible with smartphone operating system updates.
Firmware updates are often issued to fix bugs, roll out new features and improve security. Some internet-capable devices regularly check for new firmware and automatically download and install it, while other device manufacturers require the user to visit the manufacturer's website to download firmware updates and install them manually.