Welcome to the mraa wiki!

The Yocto system installed on the Intel Galileo or Edison board provides a set of libraries especially designed for the IoTDK and the Intel® XDK IoT Edition. These libraries are MRAA and UPM. MRAA is a low level library that offers a translation from the General Purpose Input/Output interfaces to the pins available on Intel Galileo or Edison. So instead of reading the raw level information from the GPIO module available on the Linux kernel, a developer can easily select a pin number and work directly with it. MRAA will take care of the underlying details. UPM is a repository of sensors representations, written in C++, and utilizing MRAA to do so. Both of these libraries have C++ bindings to JavaScript. With Intel® XDK IoT Edition, Node.JS is used to communicate with all of the GPIO Pins, libraries, and packages. For instance, the GPIO Pin 13 can be assigned with a useful line of code like var mraa.Gpio(13);

Source: https://software.intel.com/en-us/html5/documentation/getting-started-with-intel-xdk-iot-edition