Web Elements or HTML Elements and Actions on Web Elements.

i. Web Elements

Browser,
Page,

Edit Box,
Text Box,
Link,
Button,
Image, Image Link, Image Button,
Text Area, Error Message, Popup Window,
Check Box,
Radio Button,
Drop down box,
List Box,
Combo Box,
Web Table/HTML Table
Frame etc,
inline Elements,
Mouseover,

ii. Actions on Web Elements
Handle Browsers, edit box, button, lnk, checkbob etc web element.

Web Application Environment

HTML - Web Page design (UI Design)
Clicntside Scripting - JavaScript,
Serverside Scripting -VBScript
Container - ASP, JSP, etc,
XML - Data Transporter
Programming- Functionality
Web Server - Apache web server, IIS, Java Web Server etc,
Application Server - WebLogic, WebSpeare, JBoss etc, Com+, etc,
Database Server - MS SQL Server, Oracle, MySQL, SyBase, DB2, DB/400, etc,

Automated Testing using Selenium WebDriver, Create Selenium WebDriver.