The Arduino boards are programmed using a variant of the C/C++ programming language.
Example:
// Blink an LED
int ledPin = 13; // LED connected to digital pin 13
void setup() {
pinMode(ledPin, OUTPUT); // sets the digital pin as output
}
void loop() {
digitalWrite(ledPin, HIGH); // sets the LED on
delay(1000); // waits for a second
digitalWrite(ledPin, LOW); // sets the LED off
delay(1000); // waits for a second
}