Web standards
According to Best, the characteristics of Web 2.0 are rich user experience, user participation, dynamic content, metadata, Web standards, and scalability. Further characteristics, such as openness, freedom, and collective intelligence by way of user participation, can also be viewed as essential attributes of Web 2.0. Some websites require users to contribute user-generated content to have access to the website, to discourage "free riding".The key features of Web 2.0 include: