The Selenium testing tool is used to automate tests across browsers for web applications. It's used to ensure high-quality web applications — whether they are responsive, progressive, or regular. Selenium is an open-source tool.
Primarily it is used for automating web applications for testing purposes, but is certainly not limited to just that. Selenium has the support of all of the major browser vendors who have taken (or are taking) steps to make Selenium a native part of their browser. It is also the core technology in countless other browser automation tools, APIs and frameworks.
Selenium is not just a single tool but a set of different software tools each with a different approach to support the test automation of an organization. From a broader perspective previously it had four components as follows:
- Selenium Integrated Development Environment (IDE)
- Selenium Remote Control (RC)
- Selenium Grid