What is the Music Timeline?
The Music Timeline shows genres of music waxing and waning, based on how many Google Play Music users have an artist or album in their music library, and other data (such as album release dates). Each stripe on the graph represents a genre; the thickness of the stripe tells you roughly the popularity of music released in a given year in that genre. (For example, the "jazz" stripe is thick in the 1950s since many users' libraries contain jazz albums released in the '50s.) Click on the stripes to zoom into more specialized genres.
Where does the data come from?
The Music Timeline is based on album and artist statistics aggregated from Google Play Music — we define popularity by how many users have an artist or album in their music library.
What do the colors mean?
Colors are used to visually separate genres and group sub-genres, but have no other meaning.
Is this data normalized?
Yes. There's lots of data about recent music, but the information about older music is more sparse; shown directly, even major changes in the '60s are dwarfed by tiny twitches in the '90s. Additionally, there's simply more music published now! To keep the visualization legible, the overview data is normalized by the total number of albums from that year — this way, you can see and understand the timeline across all the decades.
Why does the timeline start in 1950?
The data from earlier than 1950 is too sparse to visualize in this way.
Where is the classical music?
People usually think of classical music in terms of its composition date, not its recording date — should a particular concerto recording be dated when Mozart wrote it in 1791, or when the Boston Symphony Orchestra performed it in 2009? Because of this difference, placing classical music on the timeline the same way as contemporary music looks counterintuitive, so it is omitted from this visualization.
Some albums are missing cover art!
Yes, we don't have album art to show for all artists and albums. Sorry!
Why do some albums appear more than once?
Many albums are released in slightly different versions for different countries. They might have translated titles, new art, bonus tracks, or even a different track list altogether! This makes it tricky to say precisely what defines a release, so some of these similar albums may appear separately.
What did you use to build this?
The visualization uses the D3 library and Closure Tools.

The music timeline is a project of the Big Picture and Music Intelligence research groups at Google. Contact us at .