Themes functionality allows users to use single form in multiple templates. It helps to reduce the time to create same form again and again. User can save form in form pool and those form can be assigned in different templates if same user tags or variables with similar name are already present in the template else user will get notification pop up of having different user tags. So, changes done in one form can be reflected in all the templates in which this form is selected. Thus, user don’t have to modify form of each template.