Web 2.0
1. Definition
Web 2.0 is the second generation of the web in which sites are platforms for user participation: content is created, shared, tagged and remixed by users themselves, and pages behave like desktop applications (rich, asynchronous, always up to date).
Coined by Tim O'Reilly / Dale Dougherty (2004, O'Reilly Media).
2. Core Principles (O'Reilly)
| Principle |
Meaning |
Example |
| Web as a platform |
Applications run in the browser, not installed locally |
Gmail, Google Docs |
| Harnessing collective intelligence |
Value grows with user participation |
Wikis, tagging, reviews, ratings |
| Data is the next Intel Inside |
Databases of user content are the key asset |
IMDb, Amazon reviews, Google index |
| End of software release cycle |
Software as a service, continuous updates |
SaaS dashboards |
| Lightweight programming models |
Open APIs, RSS feeds, mashups |
Google Maps API mashups |
| Software above single device |
Same service on PC, phone, tablet |
Cross-platform web apps |
3. Web 1.0 vs Web 2.0
| Aspect |
Web 1.0 |
Web 2.0 |
| Mode |
Read-only, static |
Read-write, dynamic |
| Content creator |
Webmaster only |
Every user |
| Interaction |
View pages |
Participate: comment, upload, tag, rate |
| Architecture |
Client–server page fetch |
AJAX, services, APIs, syndication |
| Examples |
Britannica Online, personal home pages |
Wikipedia, YouTube, Facebook, blogs |
| Technology |
HTML, CGI, tables |
AJAX, JSON/XML web services, RSS, mashups |
| Business |
Page views, banners |
Advertising networks, subscriptions, communities |
4. Enabling Technologies
- AJAX — asynchronous JavaScript + XML: partial page updates without reload (see Module III).
- XML / JSON web services (REST, SOAP) — machine-to-machine integration.
- RSS / Atom syndication — subscribe to updated content.
- Tagging / folksonomies — free-form user classification (
#tags, del.icio.us).
- Blogs, wikis, podcasts, social networks, crowdsourcing platforms.
- Mashups — combining data/APIs from several sites in one page (e.g. housing listings on a Google Map).
5. Typical Web 2.0 Applications
| Category |
Examples |
| Social networking |
Facebook, Instagram, LinkedIn |
| Collaborative content |
Wikipedia, Google Docs, Stack Overflow |
| Media sharing |
YouTube, Flickr, SoundCloud |
| Blogging / micro-blogging |
WordPress, X (Twitter) |
| Crowd services |
Amazon Mechanical Turk, Zomato reviews |
| Web office |
Google Workspace, Office 365 online |
6. Business and Social Impact
- Network effects — a service becomes more valuable as more users join (Metcalfe's law).
- Long tail economics — serving many niche audiences cheaply.
- User-generated content reduces content cost; advertising & freemium models.
- Trust and privacy issues — data ownership, misinformation, moderation.
- Accessibility & standards — W3C WCAG, responsive design for mobile.
7. Limitations / Criticism
- Dependence on a few large platforms (centralisation, walled gardens).
- Privacy and data-mining concerns; spam and low-quality user content.
- Browser incompatibilities; heavy client-side code; connectivity dependence.
8. Exam Points
- Define Web 2.0 and explain its characteristics/principles — 10 marks (very frequent).
- Compare Web 1.0, Web 2.0 and Web 3.0 in tabular form — 7 marks.
- Explain the technologies that enable Web 2.0 (AJAX, RSS, tagging, mashups) — 7 marks.
- Give four examples of Web 2.0 applications and their features — 5 marks.
