What are the advantages using Selenium as testing tool?

If QA Tester would compare Selenium with HP QTP or Micro Focus SilkTest, 
QA Engineer would easily notice tremendous cost savings for Selenium. In 
contrast to expensive SilkTest license or QTP license, Selenium automation 
tool is absolutely free. It means that with almost no investment in purchasing 
tools, QA Team could easily build the state of the art test automation infrastructure. 
Selenium allows developing and executing test cases in various programming languages 
including .NET, Java, Perl, RubyPython, PHP and even HTML. This is a great Selenium 
advantage, most likely your software developers already know how to develop and maintain
 C# or Java code, so they transfer coding techniques and best practices to QA team. 
 Selenium allows simple and powerful DOM-level testing and in the same time could be
 used for testing in the traditional waterfall or modern Agile environments. Selenium 
 would be definitely a great fit for the continuous integration tools Jenkins, 
 Hudson, CruiseControl, because it could be installed on the server testing box, 
 and controlled remotely from continuous integration build.