A term first defined and formulated by Tim O'Reilly, we use it to describe our current WWW sites and services. Its main characteristic is that the web moved from being read-only to the read-write state. Websites evolved into services and human collaboration plays an ever important part in Web 2.0.
From simple information portals, we now have many more types of services such as:
- Audio
- BlogPod
- Blogging
- Bookmarking
- Calendars
- Chat
- Collaboration
- Communication
- Community
- CRM
- E-commerce
- E-learning
- Filesharing
- Forums
- Games
- Images
- Knowledge
- Mapping
- Mashups
- Multimedia
- Portals
- RSS
- Wikis
Web 2.0 reached 1+ billion users in 2006 and 3.77 billion users at the time of writing this book (late 2017). Building communities was the differentiating factor for Web 2.0, allowing internet users to connect on common interests, communicate, and share information.
Personalization plays an important part of Web 2.0 with many websites offering tailored content to its users. Recommendation algorithms and human curation decides the content to show to each user.
Browsers can support more and more desktop applications by using Adobe Flash and Asynchronous JavaScript and XML (AJAX) technologies. Most desktop applications have web counterparts that either supplement or have completely replaced the desktop versions. Most notable examples are office productivity (Google Docs, Microsoft Office 365), Digital Design Sketch, and image editing and manipulation (Google Photos, Adobe Creative Cloud).
Moving from websites to web applications also unveiled the era of Service Oriented Architecture (SOA). Applications can interconnect with each other, exposing data through Application Programming Interfaces (API) allowing to build more complex applications on top of application layers.
One of the applications that defined Web 2.0 are social apps. Facebook with 1.86 billion monthly active users at the end of 2016 is the most well known example. We use social networks and many web applications share social aspects that allow us to communicate with peers and extend our social circle.