It is Open Source tool used to automate web based application.

Selenium is suite, consist of different tools as below –

Later, Selenium RC & Webdriver is combined & it becomes Selenium 2.

 

Most commonly used tool is selenium 2. Selenium IDE is not used much. Let us talk about both here.

What is Selenium IDE?

Selenium IDE provides a record & playback feature for authoring tests without learning any test scripting language. It is not used mostly since it has limitations. Only recorded scripts can be played. Selenium IDE is a fully-featured Integrated Development Environment (IDE) that installs as a plugin in Mozilla Firefox and enables developers to test their web applications through Selenium. With the Selenium IDE.

Pros – Easy to install & use, No Programming knowledge required, has built in help & reporting module.

Cons – Available only on Mozilla Firefox, can only create prototype of tests, No support to conditional operations.

            Selenium WebDriver is better than both, Selenium IDE & Selenium RC in many aspects.  Selenium WebDriver uses programming language to communicate to browser directly.  It supports various programming languages like Java, C#, PHP, Python, Perl & Ruby.

 Selenium WebDriver is not a tool like something. Selenium WebDriver has few Jar files which needs to be added in Eclipse IDE. We Will talk in detail later about this. 

Selenium WebDriver supports various browsers like IE, Firefox, Google Chrome, Opera. It can also be used on Android & iOS. Selenium WebDriver can support all operating systems where these browsers can run. 

Pros – Communicate directly to browser, Faster execution, Supports various browsers like IE, Firefox, Chrome, Safari etc.

Cons – Programming knowledge required.

More documentation on Selenium can be found on seleniumhq site- 

http://www.seleniumhq.org/