vue-router is the official router for Vue.js. It simplifies building Single-Page Applications (SPAs) by managing navigation between different views or components. Declaratively map components to routes, pass parameters, and handle user navigation with a flexible API. It features nested route/view mapping, modular component-based router configuration, route params, query/wildcard matching, and supports different history modes for various server environments. Crucially, it integrates deeply with Vue.js for a seamless development experience.