The  term was first used in pop music to describe a song composed entirely of parts of other songs, although in the online world of Web 2.0 technology, it's a website or a web application which combines content from more than one source. At a typical mashup you might have a three part page offering popular links from del.icio.us, news from Yahoo!, and photos from Flickr. If you want to see this in action take a look at the Daily Mashup.