More about the Arduino at arduino/Arduino and Wikipedia.
A "sketch" (of Arduino code) is commonly written using the Arduino IDE. The "Arduino Programming Language" at first glance looks similar to C and C++, but there are now numerous languages that can be compiled for Arudino use.
Arduino projects can range from very simple LED circuits to more complex operations involving multiple parts.
BlinkSOS.ino
A very simple sketch that blinks the SOS signal using the attached LED(s).
E-robotica.ino
Final project to demonstrate Arduino's use as a prototype Turing test by posing a question and interpreting the responder's answer.
