Here are some reasons:
- Free & Open Source: No Licence Cost
- Large Developer Communities & User Base: Supported By Google
- Cross Browser Compatibility: It support multiple browsers: IE, Firefox, Chrome, Opera, Safari
- Platform Compatibility: Window, Linux, MacOS
- Regular Development: Support for new browses and technologies provided as soon as those comes in market.
- Parallel & Distributed Testing: Using Selenium Grid.
- Support Many Languages: C#, PHP, Java, Python, Perl, Ruby
- Powerful Element Locating Techniques: ID, CSS, XPath
- Multiple Devices Testing: Android, iPhone etc.
- Regular Updates: has fresh and regular repository development.
- Easy to Implement:
- Reusability
- Resource Requirement: Less Hardware resources requirement
- Selenium IDE: Even non-programmer can write scripts using Selenium IDE
- Integration with Other tools: Easy integration with tools like Jenkins, Bamboo etc.