Web 1.0 focused on commerce while Web 2.0 emphasizes user participation and contribution. The concept of Web 2.0 emerged from a 2004 brainstorming session between O'Reilly and MediaLive International. Key principles of Web 2.0 include customization for unique users, harnessing collective intelligence by allowing users to add value through tagging, reviewing, and editing, and treating software as a perpetual beta through constant updates. Web 2.0 applications are also accessible across multiple devices rather than single devices.