Visual introduction to the Fourier Transform
One of my more difficult electrical engineering courses in college was on signals and communications. I remember there being an emphasis on Fourier Transforms. I also remember being lost a lot. I wish the demos were more visual like this video.
This is an animated introduction to the Fourier Transform, winding graphs around circles created by YouTube channel 3blue1brown.
If you are new to their channel and want to see more, a good place to start is this playlist.