Question

What is the use of DesiredCapabilities in Selenium WebDriver?

When we want to use this and how?

Answer with example would be appreciated.

Answer 1

You should read the documentation about DesiredCapabilities. There is also a different page for the ChromeDriver. Javadoc from Capabilities:

Capabilities: Describes a series of key/value pairs that encapsulate aspects of a browser.

Basically, the DesiredCapabilities help to set properties for the WebDriver. A typical usecase would be to set the path for the FirefoxDriver if your local installation doesn't correspond to the default settings.