Someone clear my doubts why triggers required

Hello, Triggers are used in styles to perform actions on a change of any property value or event fires. Triggers create visual effects on controls.

 

Refer below articles for more details.

https://www.c-sharpcorner.com/UploadFile/87b416/working-with-wpf-trigger-or-triggers-in-wpf/

https://www.c-sharpcorner.com/UploadFile/87b416/wpf-triggers/ 

 

For example check the below code xaml code which animates on button when mouse is hover on button and when button is pressed.