ITCSS – ‘Inverted Triangle CSS' is a new methodology. It involves visualising your entire CSS project as a layered, upside-down triangle.
The purpose of OOCSS is to encourage code reuse and, ultimately, faster and more efficient stylesheets that are easier to add to and maintain
The core recommendation of Dry Css is to group reusable properties, name them and then add all selectors to the group.