Introduction to Selenium
Manual Testing
Performing the testing without using any tools is known as Manual Testing. Here a tester / person will do the testing.
Automation Testing
Performing the testing with the help of tools is known as Automation Testing. Here instead of a person, a tool will perform the testing. The tool used for replacing the person is nothing but a Test Automation tool.
How can a tool perform Testing ?
Testers will do some coding and put the developed code into the Automation tool. Automation tool will perform testing with the help of the code developed by the testers.
Selenium
Selenium in simple terms is a Test Automation Tool. i.e. Instead of a person performing testing manually, Selenium tool will automatically perform the testing with the help of developed code.
Type of Applications that Selenium can automate
Selenium can only automate Web Applications (i.e. The applications which run on the browser).
Example: https://www.msn.com
Selenium cannot automate Desktop Applications or Mobile Applications (i.e. The applications which dont run on the browsers).
Example: Skype, Adobe PDF Reader and many more.
Selenium is a free tool
Selenium is a free tool. (i.e. You don’t need to pay any license amount for using Selenium tool.)
Official Website of Selenium
- Selenium.dev
Different Browsers supported by Selenium

Note: We can find the updated list of browsers in the official website of Selenium
Different Operating Systems supported by Selenium

Note: We can find the updated list of Operating Systems in the official website of Selenium
Different Programming Languages supported by Selenium

Note: Check the official website of Selenium, to get the updated list of programming languages that are supported by Selenium.
Different Components in Selenium
Selenium is not a single tool. Instead it is a combination of tools like Selenium IDE, Selenium RC, Selenium WebDriver and Selenium Grid. Out of all these tools, Selenium RC is outdated and can be ignored completely.

Different versions of Selenium
So far, Selenium got released into the market in four different versions i.e. Selenium 1, Selenium 2, Selenium 3 and Selenium 4. Selenium 1 is the older version and Selenium 4 is the latest version.

As per todays date, the Selenium 4 is the latest version and got released into the market on Oct 13, 2021
Pre-requisites required for learning Selenium
In order to understand Selenium in a better way, we need to know the below pre-requisites first:
- HTML Basics
- Locators
- Core Java
I will be explaining the above pre-requisites on the need basis.
By,
Arun Motoori