Spotify playlists somehow get it right every single time. My actual dream job would be to work as a Spotify curator.
The nerd in me got super into their curation algorithms: a mix of 3 different algorithms based on your behaviors, other users’ behaviors, and text/audio analyzation. Basically, Spotify looks at users with similar interests and recommends tracks between them. They also look at blogs/articles/lyrics to match similar messages and text with Natural Language Processing (NLP). Also, they look at the actual raw audio to find similarities in tempo, key, and loudness.