What is a Mashup?

A mashup is a web application hybrid. Mashups take information from more than one source and combine it into one application. The combination of these multiple applications makes the mashup more useful collectively than the individual applications are themselves.

A common example of a mashup is a website that uses Google Maps within its site to show visually where an address exists. So there is a web page with an address on it that becomes much more useful when another application, Google Maps, is combined with it to provide further information.

For example, see below an example from a real estate site that uses Google Maps to show the locations of local neighborhoods.