How to run parallel execution in Selenium Grid using TestNG?

Selenium Grid is a proxy server that enables the user to run tests in parallel on multiple machines. It manages different browser versions and configurations centrally. Selenium Grid allows the selenium test scripts to route the commands to remote web browsers.

When the Selenium Grid is to be used?

Selenium Grid must be used when you want to do either one or both of the following:

Tests can be run against different browsers, operating systems, and machines all at the same time: For this, you need to ensure whether the application being tested is fully compatible with a wide range of browser-OS combinations. 

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