Web 2.0 emerged from a 2004 brainstorming session between O'Reilly and MediaLive International and emphasizes user-generated content and services that reach beyond just the most popular sites. Key aspects of Web 2.0 include leveraging the contributions of users to add value through things like reviews, tags, and edits; focusing on specialized niche audiences rather than just the most popular items; and allowing for perpetual improvement of software and services.