---
title: "Harnessing collective intelligence in Web 2.0"
subject: "Web Technology"
chapter: 6
key: "semester_7/web_technology:collective-intelligence-web2"
source: https://www.bctengineer.com/q/semester_7/web_technology/collective-intelligence-web2
site: BCT Engineering
---

# Harnessing collective intelligence in Web 2.0

Web Technology · Chapter 6: Web 2.0

- Asked in: 2074 Chaitra, 5 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/web_technology/collective-intelligence-web2
- Whole chapter: https://www.bctengineer.com/md/semester_7/web_technology/chapter-6

## Question

Explain harnessing of collective intelligence in web 2.0?

## Short answer

Collective intelligence aggregates contributions from many users to create better knowledge and services. Web2.0 harnesses it through wikis, user reviews, tagging, social voting, recommendation systems, and link-based ranking that improve with usage.

## Answer

**Collective intelligence** is the idea that a large group of people, working independently or together, can produce knowledge, solutions and decisions that are better than those of a few experts. Tim O'Reilly listed "harnessing collective intelligence" as a core principle of Web 2.0: the Web gets better the more people use and contribute to it.

#### How Web 2.0 harnesses it
- **Wikis (Wikipedia):** Thousands of volunteers write and correct articles; mistakes are fixed by the crowd.
- **User reviews and ratings:** Amazon and Daraz reviews, IMDb ratings and TripAdvisor help others decide.
- **Tagging and folksonomies:** Users tag photos and links (Flickr, Delicious), creating a shared classification of content.
- **Social bookmarking and voting:** Digg and Reddit rank content by votes.
- **Blogs and comments:** Opinions, discussions and news from many people.
- **Link-based ranking:** Google's PageRank uses links made by millions of site owners as votes of importance.
- **Implicit contributions:** Recommendations ("customers who bought this also bought...") and spam filters learn from the behaviour of all users.
- **Crowdsourcing and open source:** OpenStreetMap, Linux and Stack Overflow rely on contributions from volunteers.
- **Q&A sites and prediction markets:** Quora and Yahoo Answers pool answers from many users; prediction markets combine many people's bets to forecast events.

```text
Many users --> contribute (edit, tag, rate, link)
          --> system aggregates the data
          --> better content for all users (network effect)
```

#### Benefits and issues
Benefits: low cost, wide knowledge, fast updates, and better services as the user base grows (network effect). Issues: vandalism, spam, bias, and false information, which require moderation and reputation systems.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is collective intelligence?
   A. A search algorithm
   B. A large group can produce knowledge and decisions better than a few experts
   C. Intelligence of a single supercomputer
   D. Experts working alone
   Answer: B. The idea is that many contributors yield better results than a few experts. (Key point: Concept)

2. How does Wikipedia illustrate it?
   A. Paid experts approve each edit
   B. One editor writes everything
   C. Many volunteers write and correct articles, so mistakes are fixed by the crowd
   D. Articles are generated by a server only
   Answer: C. Wikis use volunteers who write and correct each other. (Key point: Wikipedia)

3. How does Google's PageRank use collective intelligence?
   A. Links made by millions of site owners act as votes of importance
   B. It uses only the page title
   C. It counts the length of pages
   D. Users type rankings manually
   Answer: A. Link-based ranking treats links as votes. (Key point: PageRank)

4. What problems arise from collective contributions?
   A. Reduced bandwidth
   B. Expensive hardware
   C. Slow typing
   D. Vandalism, spam, bias and false information needing moderation
   Answer: D. Open contribution requires moderation and reputation systems. (Key point: Issues)

## Related in other subjects

- [Collective intelligence and KMS](https://www.bctengineer.com/question.md?key=semester_8%2Finformation_system%3Acollective-intelligence-km) — Information System, chapter 4
- [Collective intelligence pros and cons](https://www.bctengineer.com/question.md?key=semester_8%2Finformation_system%3Acollective-intelligence-pros-cons) — Information System, chapter 4
- [Meaning of collective intelligence](https://www.bctengineer.com/question.md?key=semester_8%2Finformation_system%3Acollective-intelligence-meaning) — Information System, chapter 4