1. Search Engines 19 Search Engines 19

2. Search Engines 19 We all use search engines every day But could you explain what happens behind the scenes? That’s what you could be asked about in the exam So we’ll look at how search engines work For a start, we’ll focus on the basic process…

3. Search Engines 19 How Search Engines Work Client SideServer Side DatabaseWeb Server Stage One Stage Two Stage Three You need to know about three stages…

4. Search Engines 19 How Search Engines Work Stage One: Stage Two: Stage Three Client Side Server Side Client Side You type keywords in the box & then click the button to Search The search engine uses its own database to find matches with your keywords The results are displayed on your screen

5. Search Engines 19 How Search Engines Work We all obviously know about stages 1 and 3 That’s because we see that happening on our client devices But we don’t see what happens on the server side So we’ll now focus on what happens behind the scenes with search engines

6. Search Engines 19 Search engines store info about billions of web pages… But it’s all HTML code that contains details for each page Server Side DatabaseWeb Server Index All those details are stored in the database called an Index

7. Search Engines 19 Server Side DatabaseWeb Server Index To collect all that data earch engines use special programs They are called spiders because the ‘crawl’ the Web… The spiders send back the details to store in the Index…

8. Search Engines 19 How Search Engines Work So…search engines use special programs called spiders or web crawlers or bots They ‘crawl’ or visit billions of sites and save copies of all the pages All that data is sent back and stored in a special database called an index Each search engine had its own spider programs & its own index That’s why they give different results!

9. Search Engines 19 How Google Works http://www.youtube.com/watch?v=BNHR6IQJGZs

10. Search Engines 19 Search Engines 19

11. Search Engines 19 Now we’ll focus on how people actually search That means the keywords you type into the search box And also some special techniques you can use to make searches smarter Let’s start with a reminder of how keywords fit into the search process…

12. Search Engines 19 Using Keywords Client SideServer Side Web ServerDatabase Index keywords

13. Search Engines 19 On the client side, we enter keywords Your keywords are then sent across to the server side Your keywords are compared with the Index database Back on the client, you get the results But you can get better results if you use some smart search techniques These include using quotes, minus, star and the word OR… Using Keywords

14. Search Engines 19 Use quotes to match exact phrase or quote “ ” Use minus to exclude words from search jaguar -car Use * as a ‘wildcard’ to get variations of a word *plastic Use OR to get results with both words chimp OR gorilla

15. Search Engines 19 Search Engines 19

16. Search Engines 19 Search Engines 19