CoAP is a lightweight protocol designed for resource constrained devices and networks. It allows devices to communicate over UDP using REST-like operations like GET, PUT, POST and DELETE. CoAP supports asynchronous messaging, multicast transmissions, discovery of services and resources, and can be mapped to HTTP for integration with the web. Implementations of CoAP are available in languages like C, Python, Java and .NET to enable M2M communication for devices with limited processing power and bandwidth.