In popular music, a chart-topper is an extremely popular recording, identified by its inclusion in a ranked list—a chart—of top selling or otherwise judged most popular releases. Chart-topper and related terms like No. 1 hit, top of the charts, chart hit, and so forth, are widely used in common conversation and in marketing, and loosely defined. In North America, the weekly charts from trade publication Billboard magazine are most often referenced (quite often internationally, as well), particularly the Billboard Hot 100 singles and Billboard 200 album charts, although there are many other charts and sources. Because of its value in promoting artists and releases, both directly to the consumer, and by encouraging exposure on radio, TV and through other media, chart positioning has long been a subject of scrutiny and controversy. Chart compilation methodology and data sources vary, ranging from buzz charts based on opinions of various experts and tastemakers, to charts that reflect empirical data, like retail sales. Therefore, a chart-topper may be anything from an insiders' pick to a runaway seller. The term is also used similarly to some extent in video games.