Web 2.0 brings lots of new emerging technology that helps user to get information and services from a single point of location.
Widget– It’s a small application that helps you to access feature of another website within your site. Widget always available in a ready to use format and it’s visually rich and attract user to get extra services. Widget could be available in the form of button, picture, summary and graph.
Some famous widgets are–
Mashup– Basically it’s web application hybrids and uses two or more web-based information sources to create new application and it provides user two or more services under one roof.
Mashup invented basically for Web 2.0 based application and combines content and functionality from a variety of sources using technologies including RSS and Ajax.
It’s just convenience for the user to user different kind of services within a single application.
One of best example of Mashup is - http://services.google.com/earth/green/
It’s collective efforts of Google Inc and Earth Day.