Vue.js is a progressive framework for building user interfaces that was created in 2014. It focuses on the view layer but can also be used to build single-page applications. Vue allows integration with other libraries and existing projects. The document covers what Vue is, how to get started, its templating syntax, directives, components, props, and scaling Vue with tools like Vue Router, Vuex, and Nuxt. It also discusses installation methods and provides additional resources for learning Vue.