Serial.read()

int incomingByte = 0;   // for incoming serial data
 
void setup() {
        Serial.begin(9600);     // opens serial port, sets data rate to 9600 bps
}
 
void loop() {
 
        // send data only when you receive data:
        if (Serial.available() > 0) {
                // read the incoming byte:
                incomingByte = Serial.read();
 
                // say what you got:
                Serial.print("I received: ");
                Serial.println(incomingByte, DEC);
        }
}