In computing, a web widget is a software widget for the web. It’s a small application with limited functionality that can be installed and executed within a web page by an end user. A widget has the role of a transient or auxiliary application, meaning that it just occupies a portion of a webpage and does something useful with information fetched from other websites and displayed in place. Other terms used to describe web widgets include: portlet, web part, gadget, badge, module, snippet and flake. Widgets are typically created in DHTML or Adobe Flash.

Software widget:

A software widget is a generic type of software application comprising portable code intended for one or more different software platforms. The term often implies that either the application, user interface, or both, are light, meaning relatively simple and easy to use, as exemplified by a desk accessory or applet, as opposed to a more complete software package such as a spreadsheet or word processor.

GUI widget:

In computer programming, a GUI widget (or control) is an element of a graphical user interface (GUI) that displays an information arrangement changeable by the user, such as a window or text box. The defining characteristic of a widget is to provide a single interaction point for the direct manipulation of a given kind of data. In other word, widgets are basic visual building blocks which, combined in an application, hold all the data processed by the application and the available interactions on this data.
Un-Common Web Terms
Adobe Flash Player
Client-side Scripting
Dynamic Website
IP Address
Mobile Computing
Server-side Scripting
Static Website
Streaming Media