Web 2.0 refers to more interactive and user-driven websites where users can generate and share content. It involves technologies like AJAX, social networking, user-generated content, and mashups. The document discusses the components and technologies of Web 2.0, trends in Internet usage, emerging technologies like enterprise Web 2.0 and mobile Web 2.0. It outlines opportunities for telecom companies to offer innovative Web 2.0-based services and discusses BT's successful Web21C SDK platform that allows developers access to core network services.