Why would we want to do that? Please think carefully about what this will mean.

If we add images in our images folder other than joomla default images it is tracked by git so if we create pr that images will come
considering this I add images folder in gitignore .As I am beginner in joomla ,Please give a reason why images folder should not ignore ,Thanks in advance

When we add the images finder to gitignore, we can’t maintain anymore on GitHub the images provided by the CMS core. When you work on a git clone of the CMS and add new images, you should clean up your branch before working on pull requests, or better use different branches for testing and making pull requests, and the testing branches you reset with git clean command so you never check in accidentally any stuff you have added for testing, like images or whatever.

Closing for the reasons stated above.

In addition any additional images will be added to your pull request ONLY if you commit them to your branch