Tuner apps are digital tools designed to help musicians and music enthusiasts tune their instruments accurately. They use the device's microphone to detect the pitch of a sound and provide visual feedback, indicating whether the note is in tune, sharp, or flat. These apps are commonly used for instruments like guitars, violins, and pianos. Many tuner apps offer additional features, such as metronomes, pitch pipes, and even tuning presets for specific instruments. They are available on various platforms, including smartphones and tablets, making them accessible for musicians on the go.