Call Waiting is a telephone feature that alerts you when someone is trying to reach you while you are already on a call. When a second call comes in, you hear a beep or tone, indicating that another caller is trying to connect. This allows you to decide whether to continue your current conversation or switch to the new call. To use Call Waiting, you typically press a specific button or combination of buttons on your phone to switch between calls. This feature is commonly available on both landline and mobile phones, making it easier to manage multiple conversations without missing important calls.