The Arduino alarm buzzer is a component that generates sound to signal an alarm. It is a digital component that can be connected to digital outputs, such as pin 9 in the example code provided [1] [6]. The code uses the "tone" function to send a 1 kHz sound signal to the buzzer, and the "noTone" function to stop the signal [2]. This creates a short beeping sound that loops continuously.

The buzzer can be used for various projects, such as security alarms [4] or intruder alarms [8]. For example, in one project, light shining on a Light Dependent Resistor (LDR) activates the buzzer, triggering an alarm [7]. It's also possible to play specific melodies through the buzzer, as requested in a forum post [5].

The specific buzzer used in the contexts provided is a 5V 2 Terminals Passive Electronic Alarm Buzzer Electromagnetic Beeper AC Impedance for Arduino [3]. However, the code and setup can be adapted for other types of buzzers as well.