Embedded software is computer software that is written to control machines or devices that are not typically thought of as computers, commonly known as embedded systems. It is specialized for the particular hardware that it runs on and has time and memory constraints. Unlike standard computers that generally use an operating system such as macOS, Windows, or Linux, embedded software may use no operating system or a wide variety of operating systems can be chosen from, typically a real-time operating system. Code for embedded software is typically written in C or C++, but various high-level programming languages, such as Java, Python, and JavaScript, are now also in common use to target microcontrollers and embedded systems.

Embedded software can be very simple, such as lighting controls running on an 8-bit microcontroller with a few kilobytes of memory, or it can become very sophisticated in applications such as routers, optical network elements, airplanes, missiles, and process control systems. It is used to control the limited, set functions of hardware devices and doesnt generally need input; it is not typically worked with directly by users. Its functions are activated by external controls, either external actions of the device itself or remote input.

Embedded software is developed from scratch to run exclusively on that hardware in that precise configuration, making embedded software design a very specialized field that requires deep knowledge of hardware capabilities and computer programming. Almost every device made with circuit boards and computer chips has these components arranged into a system that runs embedded software. As a result, embedded software systems are ubiquitous in everyday life and are found throughout consumer, industrial, automotive, aerospace, medical, commercial, telecom, and military technology.