Imaginary numbers, discovered hundreds of years ago, turn out to be extremely useful in computing when analyzing the electromagnetic radiation we use in radios and wifi, audio signals for music and voice communication, alternating current power supplies, GPS, and MRI machines. Not to mention, the weird world of quantum physics.
Source: https://www.sciencefocus.com/science/a-brief-introduction-to-imaginary-numbers
Video About Imaginary Numbers: https://www.youtube.com/embed/6xDG5pEv3Kc