Google uses multiple techniques like crawling pages, analyzing search queries, and collecting data from its toolbar and browsers to gather information about websites. This includes analyzing the layout, content to advertising ratio, relevance to search terms, repeat visits, bounce rates, social signals, time on site, number of pages viewed, and comparing this data to evaluations from human evaluators. The goal is to assess website quality and determine how highly to rank sites in search results.

1. SEO
Here you will find good examples of what Google collects in order to assess
whether a web site has the quality to appear higher in search results.

2. Googlebots use multiple sources and techniques
to gather information on our Web sites. For
example:
1. Crawling a page
2. Considering what the people are searching for
3. The free Google toolbar, Android browser &
Chrome

4. Through crawling of a web page and
content analysis , Googlebot collects
and analyses the following
information:

5. Layout of the page: What is the
quality of the web design of a
particular page compared with that
of the pages that are considered
positive/negative by Google
evaluators.*

7. Content/Advertising: What is the ratio of
content to advertising?
Relevance: To what extend is the content
of the webpage related to the search term
and what the man who seeks really meant?

8. Through analysis of the behavior of
web visitors who have arrived at a
particular site from search results,
Google considers:

10. Repeat visits: With what frequency seekers
return to your results or click on another page
after they visit your site?
Hits: What percentage of people who click on
your page link then click on other search
results?
Social signals: Do users mark your page as a
spam, or they rather give it a (+1)?

11. Through the data that is gathered
from Google toolbar, Android and
Chrome, search engines consider:

13. Time spent online: How long time the average
visitor spent on your webpage
Number of visited pages: Do visitors look at other
pages after they arrive on your site?
Comparison: How does the data on visitor
behavior relates to the data that is provided by
the evaluators*?

14. Evaluators* Google users, evaluating the Web
according to pre-set criteria. Google engineers
put these assessments into the search engine
algorithm. This approach was introduced by
Google Panda algorithm, through which
Google emphasized the quality of web content.

16. www.madamseo.com
Cheers ;)