How do search engines work? | Year 3 Computing PDF Download

Searching the world wide web

• The World Wide Web consists of nearly 2 billion websites.
• Each website has a unique URL, or web address.
• You are familiar with the URLs of some of your favorite webpages, which you use to visit them.

What are search engines?

• A search engine is a program that locates webpages on the internet.
• You enter the words you want information about.
• The search engine searches for webpages containing that information.

How do search engines work?

• A search engine is similar to a librarian.
• At the library, you can ask a librarian to find books on your favorite topic.
• The librarian searches through an index to locate the books.
• The index contains key details about each book in the library.
• The librarian then provides you with the titles of the books they found.

How a search engine works?

• You enter keywords or a question into the search engine.
• The program searches the index for webpages related to your keywords or question.
• The program determines which pages are most useful to you.
• The program ranks the webpages, placing the most useful at the top.
• The search engine displays the webpages it has found for you.

Are all search engines the same?

• Function of Search Engines: Search engines play a vital role in helping us find information on the internet. They work by allowing users to input keywords or questions, which the search engine then uses to locate relevant webpages.
• Diversity Among Search Engines: Not all search engines are identical; they have individual features and specialties. Some search engines focus on specific types of content like news, facts, or images, while others cater to a younger audience by filtering out inappropriate material.
• Search Strategies: Effective searching involves using the right keywords. For instance, searching for "Wellington" could yield results related to the capital city of New Zealand, Wellington boots, or a type of food.
  • Capital city of New Zealand
  • Wellington boots
  • Type of food
• Enhancing Search Precision: To refine search results, additional keywords can be added. For example, typing "Wellington, New Zealand" can provide more accurate and targeted information.
• Specialized Search Engines: Some search engines are designed for specific purposes, such as searching for news, images, or educational content. These specialized search engines can provide tailored results based on the user's needs. 

How Search Engines Create an Index?

• A search engine creates an index using a web crawler.
• A web crawler is an automated program that browses the web and collects information about the webpages it visits.
• Each time a web crawler visits a webpage, it copies the page and adds the URL to the index.
• It also includes details of the page content, keywords, and types of media.
• When you enter words into a search engine, it searches its index for matches to your words.

How do search engines order results?

• Search engines use algorithms to rank the list of webpages they return.
• The webpages at the top of the list are typically the most useful to you. All these webpages have been visited by the search engine’s web crawlers.
• So, when you use a search engine to find information, remember that web crawlers created an index and an algorithm ranked the results.