Contiki is an open-source, lightweight operating system designed for resource-constrained devices in the Internet of Things (IoT). It supports multitasking, dynamic loading of programs, and includes a built-in TCP/IP stack with IPv6 support, making it suitable for low-power wireless communication. Contiki’s modular architecture and event-driven kernel allow it to run on a variety of hardware platforms, including microcontrollers and legacy computers. It also features the Cooja network simulator for testing and development.