Meteor is a full-stack JavaScript platform for building mobile and web applications using a single codebase. It allows for real-time updates without page refreshes through its live data synchronization and reactive rendering. Key features include automatic data synchronization across clients, a minimalist structure, and support for mobile development using Cordova. The presentation provided a code demo and overview of Meteor's architecture and components like Blaze and Livequery before discussing upcoming features like support for ES6 modules and GraphQL integration.