Selenium it is a automation tool used to automate web pages , it is one kind of package in python.selenium is a framework which helps us to automate the web application,it is a package we can install using pip install selenium.
It does not require any monitoring or human it is time saving,time consumption is less,it is an open source tool we can install freely.

ADVANTAGES:
->Language and framework support.
->supports various operating system.
->Easy for implementation.
->flexibility and more efficient with selenium feature it will reduce
duplicate.
->minimize complication and improves maintainability.

components of Selenium S it has all the below listed:

Selenium Integrated Development Environment (IDE)
Selenium Remote Control (RC)
WebDriver
Selenium Grid

1.Selenium IDE: Selenium IDE is a Firefox add-on that enables testers to record and playback the recorded automated tests. Selenium IDE is easy to use and lets you create and run automated tests quickly. Selenium IDE Chrome also includes a built-in debugger that enables you to troubleshoot your tests. To use Selenium IDE, you first need to install the Selenium add-on for Firefox or Chrome. You can then open Selenium IDE by clicking on the Selenium icon in the Firefox or Chrome toolbar.

2.Selenium RC: Testers needed to install local copies of both Selenium Core program code and the web server containing the web application being tested so they would belong to the same domain.The Web-Driver proves to be better than Selenium IDE and Selenium RC in many aspects. It implements a more modern and stable approach in automating the browser’s actions. Web-Driver, unlike Selenium RC, does not rely on JavaScript for Selenium Automation Testing. It controls the browser by directly communicating with it.
The supported languages are the same as those in Selenium RC.

C#
Java
PHP
Python
Perl
Ruby

3.Selenium Web-Driver: Selenium Web-Driver is an open-source tool used for automating web browser interaction from a user perspective. With it, you can write tests that simulate user interactions with a web application. It is available for many different programming languages.

Web-Driver provides a powerful and flexible test automation framework that enables you to create automated tests for your web applications easily. It also includes several over-the-top features, such as automatically discovering elements on a web page and capturing screenshots of your tests.

4.Selenium Grid: Selenium Grid distributes your tests across multiple machines or virtual machines. Selenium Grid enables you to test parallaly on various devices or Virtual machines, allowing you to scale your test automation quickly. Selenium Grid is a crucial part of the overall Selenium testing suite and will enable you to execute your automated tests much faster.

The Selenium Server is a part of Selenium Grid that can be installed locally on your device or hosted on a separate system/server.

Why do we use selenium for automation?

Open source, free to use, and free of charge.
Highly extensible and also user easy.

It can tests in different browsers.
Supports various operating systems.
Can execute tests while the browser is minimized.
Supports mobile devices.
Can execute tests in parallel.

Efficient and accurate web application testing.
The ability to test your web application on multiple browsers and operating systems.
The ability to run more than one test at the same time.
With a Selenium Grid, you can significantly reduce your time to test your web application. And by using a Selenium Grid, you can ensure that your web application is fully functional before releasing it to users. So if you want to improve your web application testing, consider using a Selenium Grid. It’s one of the best ways to automate your web application testing!

Selenium is an all-in-one tool that can help you streamline your agile testing process. By following the tips below, you can ensure that your automated tests are practical and efficient and that they play a valuable role in your agile development cycle:

Automated tests should be run frequently as part of the continuous integration process.

Tests should be written to allow them to be run quickly and easily.
Tests should be designed to test a specific functionality or behavior and should not be too complex.
New features and changes should be accompanied by automated tests to ensure that the application functionality remains intact.
Automated tests should supplement manual testing rather than replace it altogether.

In agile development, Selenium Testing is typically used in the following ways:

The regression testing process, to ensure that existing features continue to work as expected after new code has been added.
To verify that new features are working as expected before they are released to production.
To help identify and troubleshoot bugs in web applications at both business and development levels before releasing the app.