Selenium is an open source, automated tool used to test web applications across various web browsers.

It can test all web applications against various we browsers like Firefox, Chrome, Opera, Microsoft Edge, etc.. and tests can be coded in several programming languages like Python, JAVA, Ruby, Perl..

Selenium Web Driver

Selenium Web Driver is an open - source library which is the key component of Selenium automation framework.

It is used to automate the testing process of web applications in real time.

Selenium Architecture

1. Selenium IDE

• Stands for Integrated Development Environment

• A web - browser extension

• This extension allows us to record the entire automation process of a
  web application.

• But it cannot run the automated test reports.

1. Selenium Remote Control

• Comprises of client libraries, and a server that opens and terminates
  the browser by default.

• In current versions of selenium Selenium remote control is outdated and
  replaced by Selenium Web Driver.

1. Selenium Web Driver

• An interface between the programming language (used for automation scripts) and web browser for the execution.

• It is composed of

Selenium Client Library

The programming language commands to write automation scripts.

Selenium API

Set of rules and regulations which python uses for the automation
scripts.

JASON Wire Protocal

The automation scripts that we write gets converted into JASON and then
transmitted to web browser for execution of commands.

It uses TCP-IP/http protocols.

Browser Driver

Acts as a connection between selenium scripts and web browser.

Eg - http://developer.chrome.com/docs/chromedriver

1. Selenium Grid

• Selenium Grid is used to run parallel tests on multiple devices running different browsers at the same time.

Python Virtual Environment

A place where we save our libraries by creating an isolated environment.

It creates a self contained environment for each individual projects when we work on more than one project, allowing us to manage the dependencies independently without affecting each other.

Significance of Python Virtual Environment based on the example of working in multiple projects in real time

• Isolation

Provides an isolated environment for each project, preventing
dependency conflicts.

• Portability

Allows us to move projects between systems.

• Efficiency

It only install dependencies required for the specific project working
on, thus reducing resource storage.

• Reproducibility

Provides a consistent virtual environment for each individual projects.

• Improved Security

Provides a sandboxed environment, reducing the risk of compromising the
system wide python environment.

• Flexibility

Allows us to use different versions of python and dependencies for each
project.

• Testing and Debugging

Virtual environment provides a consistent environment for testing and
debugging, ensuring the consistent results in automation.