What is an Event? Think about a doorbell. Most of the time, nothing happens. The doorbell just sits there, waiting. Then someone presses the button — and the bell rings. What happened? Something occurred . Someone pressed the button. That act of pressing — that is an event . The event caused a response: the bell rang. The Simple Pattern Every event follows the same pattern: Something happens → A response is triggered What Happened (Event) What Happened Next (Response) --- --- Someone pressed the doorbell The bell rang inside the house A smoke alarm detected smoke The alarm started making noise The alarm clock reached 7:00 AM It started buzzing You tapped play on Spotify The song started playing Someone sent you a message Your phone vibrated In every case: something happened first, and then something else happened because of it . The first thing is the event. The second thing is the response. What Makes Something an Event? An event is: 1. Something that happens — it did not exist before, and now it does 2. Something a programme can notice — the computer has to be watching for it 3. Something that triggers a response — when the event occurs, specific commands run Events can come from many places: You — a tap, a click, a keypress, a swipe, a voice command Time — the clock reaching a certain time, a timer running out Sensors — a motion sensor detecting movement, a temperature sensor reading too high Other programmes — a message arriving, a file finishing download, a payment being completed Events vs Commands: What Is the Difference? You learned in the Commands series that commands are things you tell a computer to do. Events are different — they are things that happen to the computer (or the device), from inside or outside. Command Event --- --- --- Who starts it You, actively Something that occurs (you, time, sensor, another system) Example "Play this song" "Someone tapped the play button" What it does Directly triggers an action Triggers a listening programme to run its commands A command is an instruction you write. An event is a thing that happens that the programme detects. The Doorbell, Revisited Let us trace a doorbell event carefully: 1. The event occurs: someone presses the button outside 2. The programme notices it: the doorbell circuit is always listening for a button press 3. The response runs: electricity flows to the bell mechanism, which vibrates and makes a sound 4. The event is over: the doorbell returns to waiting Step 2 — the programme is always listening — is important. The doorbell does not ring when no one presses the button, even though the wiring is connected. It is waiting. Listening. Ready to respond the moment the event occurs. This idea of a programme waiting and watching for a specific event is called an event listener . It is one of the most important concepts in programming. Without Events, Programmes Are Stuck Imagine a music app with no events. The app opens — and then what? Nothing happens. There is nobody pressing play, nobody selecting a song, nobody turning up the volume. Events are what make interactive systems interactive . They are how programmes know when to do something — because something just happened. In the next post, we will look at just how many events are happening around you all the time, in devices you use every day. ✅ Summary An event is something that happens — a tap, a click, a timer, a sensor reading — that a programme can notice and respond to. Every event follows the pattern: something happens → a response is triggered . Events can come from users, from time, from sensors, or from other systems. A programme that listens for events is ready to respond the moment one occurs. Events are what make computers interactive — without them, programmes would just sit still. Coming up next: Events Are Everywhere — from smoke alarms to automatic doors to phone notifications, events are all around you.