WordPress Plugin Themify Popup Description:
Themify Popup allows you to display beautifully responsive pop up windows on any page of your website. You can use it to showcase newsletter subscription forms, promotional announcements, or general lightbox content. You can allow popups to show on the entire site, or on certain posts, pages, categories, specific user roles, or even at specific times (so you don’t have to manually disable the popups). It’s fully integrated with the Themify Builder allowing you to design any popup layout on the frontend with the drag & drop interface and live preview.
Related to WordPress Plugin Themify Popup
WPSlug.com data has a list of 4 WordPress CMS installations Using the WordPress Plugin Themify Popup.