In order to handle software regardless of device boundaries, it is essential to have open interfaces:

• Web 2.0 is open.
• Most applications are based on Open Source software.
• By using open interfaces (APIs) offers and data can be combined with each other.
• RSS Feeds and Widgets allow for the integration of contents on special sites.
• Standards are given and are constantly being further developed by the World Wide Web Consortium.

Open interfaces combine different offers.

(According to O’Reilly: Web 2.0 for Participation)