Web mashups characterize the second generation of Web applications, known as Web 2.0. They are composite applications, usually generated by combining content, presentation, or application functionality from disparate Web sources.
Typical components that may be mashed-up, i.e., composed, are RSS/Atom feeds, Web services, programmable APIs, and also content wrapped from third party Web sites. Components may have a proper user interface that can be reused to build the interface of the composite application, they may provide computing support, or they may just act as plain data sources. Content, presentation and functionality, as provided by the different components, are then combined in disparate ways: via JavaScript in the browser, via server-side scripting languages...