Ext is a JavaScript library for building interactive web applications using techniques such as AJAX, DHTML and DOM scripting. Originally built as an add-on library extension of YUI, Ext includes interoperability with jQuery and Prototype. As of version 1.1, Ext retains no dependencies on external libraries, instead making their use optional.

GUI controls

Ext includes a diverse set of GUI-based form controls (or "widgets") for use within web applications, these include:

  • Text field and textarea input controls
  • Date fields with a pop-up date-picker
  • Numeric fields
  • List box and comboboxes
  • Radio and checkbox controls
  • HTML editor control
  • Grid control (with both read-only and edit modes, sortable data, lockable and draggable columns, and a variety of other features)
  • Tree control
  • Tab panels
  • Toolbars
  • Desktop-application-style menus
  • Region panels to allow a form to be divided into multiple sub-sections
  • Sliders
  • Flash charts

Many of these controls are able to communicate with a web server using AJAX.

Source: Wikipedia