Learning to Program

When

One of the great features of user interfaces is that they react to our actions. When I click the Send button in my email client, the email gets sent. When I rotate my phone, the screen orientation flips. Sometimes we want the computer to do something at a certain time. My calendar gives me a reminder 15 minutes before a meeting starts. My phone starts making sound at 5:00 AM to let me know it’s time to wake up (okay, we might not necessarily want the phone to wake us up). Other times, we want the computer to do something after a certain amount of time has passed. Gmail deletes a spam message 30 days after it arrives in my inbox. In each of these cases, the computer executes code “when” something happens.