We use some techniques very similar to what a speech recognizer does. It will take the audio and will run signal processing algorithms over it and try to extract out some key features that describe the music. We then use some machine-learning techniques basically to teach this system how to recognize music that is both similar and dissimilar. So at the end, we have a music similarity model and this is the neat part. We can then use this music similarity model to recommend music that sounds similar to music that you already like.