1. Mr C Johnston ICT Teacher www.computechedu.co.uk G042 – Lecture 02 Using Logical Operators To Aid Searching

2. Session Objectives Understand how different logical operators can be used to narrow down searches when trying to find information on the internet.

3. What Is A Search Engine Manual navigation of millions of web pages and thousands of newsgroups is impractical, A search engine is a catalogue of web pages, It stores details about site which searches can be carried out on, A search engine therefore is a user interface which allows you to search a huge database containing lists of web pages and newsgroups, Search Engines comprise of three main components: Sourcing the data Indexing and creating the database The search engine application

4. Search Engine Application Main user interface is written in HTML with a box for users to enter a search string into, When the search button is pressed the search string is processed by a computer programming language and a search is executed on the search engine database, The results are generated and displayed in a dynamic HTML page using a mixture of programming code and HTML. Machine With Internet Connection Search Engine Web server Search Engine Request Search Results Returned Database Queried Query Results Search Engine Database

5. Searching Using Operators Searches can be made more efficient by pulling out key words and linking them together with Boolean operators. Operators Include: AND(+) Finds pages with all the specified words in (not necessarily in order) NOT(-) Finds pages that don’t include words OR Finds pages which contain at least one of specified words “ “ Finds pages with the exact phrase in * Wildcard - not that useful (see example next slide)

6. Rules Type operators in CAPS with space between the keywords. When using + / - set watch where the spaces go…. +welding +process +Saturn –car Spaces between keywords but not between keywords and operators.

7. Some Examples Use phrases, not single words and enclose in quotes. Finding websites about the the Roman invasion of Britain Roman Invasion of BritainPages Found: 665856 RomanPages Found: 111130 “Roman invasion of Britain”Pages Found: 114 Use + for words that must occur and — for words that must not occur. Finding websites about the Amazon Rainforest AmazonPages Found: 204880 Amazon –bookPages Found: 106940 +Amazon –book +rainforestPages Found: 10905 Think about word variations and plurals. educationPages Found: 485630 educat* Pages Found: 3484050 (educational, educator, educated & education will appear)

8. Topic Exercise Complete this topics reading: http://www.googleguide.com/ http://www.learnwebskills.com/search/engines.html Download this topics worksheet and complete it.