Google has now become part of our lives and you can't ignore it: 92% of searches made on the net (Gs.statcounter, 2020) use the engine patented by the two students of Stanford University, Larry Page and Sergey Brin.

And it's not just Google Search as you know: a whole infrastructure of services, applications, operating systems is produced by the Mountain View company.

In this video, we try to take an overview of the tool to understand what to expect with regard to our study needs.

Google crawlers are software that continuously scans and analyze information on the World Wide Web and build an index of content available on the network. Doing this they classify them according to statistical-mathematical formulas that then indicate the degree of relevance to a given search key.

You can watch this interactive video provided by Google itself to understand how the search works. If you just want a taste instead, watch the official presentation: it is in English, but you can activate the subtitles in Italian (youtube menu bar, at the bottom of the video):

In Google can we find the whole World Wide Web?

No, many pages are not indexed by Google search engine. The reasons can be various, for example:

• who wrote the page included a file with a specific command that denies permission to register that part of the network to web crawlers, also called spiders. Most of the time because they contain data that is not meaningful, or else sensitive data like for example, corporate networks.
• Then there are password-protected pages for example because it is paid content, as in the case of databases, or content protected by copyright. However, some publishers allow the indexing of their contents to search engines, reserving access to full text only to subscribers.
• Other sites are not present in the index simply because no other site links to their pages, therefore the crawlers do not get there.

The pages that for one reason or another are not accessible to search engines make up what is called Deep Web or Invisible Web, and constitute a very significant part of the web.

However, the Deep Web is not to be confused with the Dark web, which is a subset of the deep web, accessible only through the use of specific software and usually deliberately shielded because it conveys information that is at the limit of legality.

How to make Google search more effective?

There are some tricks that help to improve our Google searches. In this video, we propose you a quick review. 

If you prefer you can watch the video summary by clicking on the button at the bottom of the page.