Advantages and Disadvantages of selenium automation tool

Advantages of Selenium

1. Open Source
2. Supports all browsers like IE, Firefox, Mozilla, Safari
3. Supports all Operating Systems.
4. Supports all programming languages Java,Ruby,C# and Python.
5. Run multiple tests at a time.

Disadvantages

1. Identifying the locators that support common attributes like id, names etc as well as XPATH, javascript DOM and others (Use firebug for finding the locators)
2. Detailed results are not available
3. Selenium IDE does not supports loop and data driven testing
4. No Option to verify the images.

What is the need of Test automation for web application

1. Frequent regression testing
2. Rapid feedback to developers
3. Virtually unlimited iterations of test case execution
4. Support for Agile and extreme development methodologies
5. Disciplined documentation of test cases
6. Customized defect reporting
7. Finding defects missed by manual testing