Unit 7.6
The World Wide Web and Search Engines
Learning Objectives 🎯
By the end of this chapter, you will be able to:
- ✅ Differentiate between the Internet and the World Wide Web.
- ✅ Describe the roles of a web browser and a web server.
- ✅ Explain the basic function of a search engine.
Internet vs. World Wide Web
They are not the same thing! It's a common misconception.
The Internet 🌐
- The global network of computers.
- The physical infrastructure (cables, routers, servers).
- Analogy: The road network of a country.
The World Wide Web (WWW) 🕸️
- A service that runs on the Internet.
- A system of interlinked documents.
- Analogy: The houses, shops, and destinations along the roads.
⚡ Key Idea: The Web uses the Internet to exist, but the Internet is more than just the Web (it also supports email, FTP, etc.).
Key Components of the Web
How do we access information on the Web? Through a client-server model.
Web Browser (Client)
Software on your device used to view websites.
- Requests web pages.
- Renders HTML, CSS, and JavaScript.
- Examples: Chrome, Firefox, Safari.
Web Server (Server)
Software on a remote computer that stores websites.
- Listens for requests from browsers.
- Serves web pages upon request.
- Examples: Apache, Nginx.
The Web Address: URL
Every resource on the Web has a unique address called a Uniform Resource Locator (URL).
Anatomy of a URL
https://www.tu.edu.np/results
- https:// - The protocol (HyperText Transfer Protocol Secure).
- www.tu.edu.np - The domain name (Tribhuvan University, Nepal).
- /results - The path to a specific resource on that server.
The Problem: Information Overload
The Web contains billions of pages. How can we find anything?
🔍 Enter Search Engines
Definition: A search engine is a software system designed to search for information on the World Wide Web.
How Search Engines Work: A 3-Step Process
1. Crawling 🕷️
Automated "spiders" follow links to discover pages.
2. Indexing 📚
Content is analyzed and stored in a huge database (the index).
3. Ranking 📊
An algorithm sorts results by relevance and authority.
Step 1: Crawling
Crawling: The process of systematically browsing the web to discover new and updated content.
- Automated programs called "spiders" or "crawlers" perform this task.
- They start with a list of known URLs and follow hyperlinks on those pages to find new ones.
- This process is continuous to keep up with the ever-changing web.
Step 2: Indexing
Indexing: The process of storing and organizing the content found during crawling.
- Once a page is crawled, the search engine analyzes its content (text, images, keywords).
- This information is stored in a massive database, like a giant library index for the entire web.
- The index allows for nearly instantaneous retrieval of relevant pages.
The purpose of the index is speed. Searching the entire web in real-time is impossible!
Step 3: Ranking
Ranking: The process of deciding the order in which to display results for a user's query.
- When you search, the engine queries its index, not the live web.
- A complex algorithm evaluates hundreds of factors to determine relevance.
- Factors include keywords, page authority, user location, and freshness of content.
- Examples: Google Search, Bing, DuckDuckGo.
Practical Application in Nepal
Search engines adapt results based on your context, like location.
Try This Search
Search for "restaurants near me" on your phone.
- The search engine uses your location in Nepal (e.g., Pokhara, Kathmandu) to provide local results.
- Now search for "latest news". You'll likely see results from Nepali news portals like The Kathmandu Post or Onlinekhabar ranked highly.
- This is the ranking algorithm at work, prioritizing local relevance.
Key Takeaways ⚡
- The Web is a service that runs on the Internet. They are two different things.
- A web browser (client) requests pages from a web server.
- Search engines find information through a three-step process: crawling, indexing, and ranking.
- The index is a critical database that makes fast searching possible.
Thank You!
Any questions?