The "deep web" is what you cannot retrieve from Google. A research study by Bright Planet says the deep web is 500 times larger than the surface web. See "Understanding the Deep Web in 10 Minutes”. This invisible web is made up of 1,000s of specialized databases. Google cannot index these because search results are created dynamically. Examples include the contents of library catalogues, journal indexes, and any page that is generated in response to a unique query.
A Google engineer explains How Search Works.
AND is assumed and does not need to be typed.
Quotations for phrases: “middle ages”
intitle: Finds the word or phrase immediately after the colon in the title e.g. intitle: “genetically modified foods” Canada
allintitle: Works the same way as intitle: but looks for every word in the title.
Plus/minus to require or remove terms. e.g. strategies "first day" activities +secondary school
OR in capitals for synonyms. e.g. “middle ages” OR medieval; globalization OR globalisation
Use * within a phrase for characters or words: Pierre * Trudeau
~in front of a word for synonyms: “middle ages” ~weapons
Definitions: Use define: for words in the order in which you type them. Define:”greenhouse gases”
Use the date options to limit your results to the last day, week, month, year or within a custom date range. This tends to work best with blogs and news sources although Google is getting better at identifying dates generally. To see the date option click on ‘Search tools' in the menu above your search results, and then on the “Any time” option in the menu that then appears.
An essential tool for taming Google. Google automatically looks for variations of your terms and using double quote marks around terms or phrases does not always work. In addition Google no longer looks for all of your terms in a document. If you want Google to run your search exactly as you have typed it in, click on ‘Search tools' in the menu above your results, then click on the arrow next to ‘All results' and from the drop down menu select Verbatim.
Add level: secondary elementary; possibly include subject – physics, music
Add type of material:
Use Control F on any page to serach for a word.
Alternatively, In Google Chrome, select the tools icon in the top right corner and select Find to search page results for a term. Internet Explorer includes Find under Edit in the top menu.
Use the filetype: command or the file format option on the Advanced Search screen to limit your research to PowerPoint for presentations, spreadsheets for data and statistics or PDF for research papers and industry/government reports.
Note that filetype:ppt and filetype:xls will not pick up the newer .pptx and xlsx formats so you will need to incorporate both into your strategy, for example,
filetype:ppt OR filetype:pptx
Use the site: command or the domain/site box on the advanced search screen to limit your search to particular types of site.
Examples: Remove commercial sites: -site:.com
“global warming” site:.edu
Word order changes the order in which your results are displayed. Place priority words at the start of the search.
Use the “cached” feature for missing URLs when a link no longer works.