selenium

     1)selenium is an open-source, automated testing tool used to 
       test web application across various browsers.
     2)Selenium can only test web applications, unfortunately, so 
       desktop and mobile apps can't be tested. 
     3)However, other tools like Appium and HP's QTP can be used to 
       test software and mobile application.

Selenium used for automation:

          i) Selenium is an open-source automation framework 
             created in the year 2004 by Jason Huggins.
          ii)It is written purely in Java
         iii)It is used to validate the web applications only
         iv)Selenium can be used not only with Java but also with 
             Python, C#, JavaScript, Ruby etc,
          v)Selenium is just an automation framework only. 
            For testing you need other frameworks like  
            pytest, Python Behave.
         vi)It allows users to test their websites functionally on 
            different browsers.
        vii)Perform cross browser testing to check if the website 
            functions consistently across different browsers.
       viii)Selenium is an open-source suite of tools and libraries 
            that is used for browser automation.