A computer-implemented process comprises identifying, by a computer server system, a base topic for a personalized media stream for a user of a computer system; identifying, with the computer server system, a plurality of media items associated with the base topic using a plurality of different and independent categories of media categorization data, wherein each of the categories of media categorization data is assigned a weighting; building a collection of candidate media items from the identified plurality of media items; ordering the collection of candidate media items to form a personalized media stream; and providing the ordered collection of candidate media items for playing to the user.