What do you mean by Modal plugin that is used for in Bootstrap?
When there is a need to cover a parent window, a child window can be created using a modal. Developers generally use a custom Jquery Plugin to create a Modal on Bootstrap. Modal windows are best when it comes to improving the experience of a user and also adding more functionality. The modal windows can be simply created with the help of a modal plugin.
🔗Reference : stackoverflow.com
🔗Source: Bootstrap Interview Questions and Answers for Freshers and Experience