Arduino is an open-source prototyping platform based on easy-to-use 
hardware and software. Arduino boards are able to read inputs - light on
 a sensor, a finger on a button, or a Twitter message - and turn it into
 an output - activating a motor, turning on an LED, publishing something
 online. You can tell your board what to do by sending a set of 
instructions to the microcontroller on the board.
  
Arduino IDE 1.6.12 Changelog
[ide]
 Refactor Editor code, solving some long standing bugs and cleaning up everything.
 Add initial Cloud API integration. When plugging a new board, if an additional core is needed, the user will be prompted to install it
 Improved examples menu organization.
 Recompiled arduino-builder with Go 1.7.1 to avoid crash on OSX Sierra
[core]
 avr: Add support for internal 2.56V and 2.56V ext. cap analog references on the ATtiny25/45/85.
 Added String::toDouble().
 Update to avrdude 6.3 with patch to ignore unused fuses (burn bootloader works also wih outdated cores)