What are Google Analytics Cookies made of?

Good day.
Recently, one of our customers expressed a desire to receive additional information about visitors to their site, more specifically, about the people who filled out the contact form. This is a large European company and they would like to “filter” their potential customers. Let me explain with an example - let's say they decide to organize an exhibition of their equipment in Hungary and they need to decide which of the Hungarians who left them their contacts is probably a worthwhile client, and who “passed by”.
The main indicators of "reliability" of the client for us are: the number of visits to the site, the time spent on the site, the number of pages viewed. All this information we received from Google Analytics Cookies.

What are cookies from Google?

If someone suddenly does not know what a cookie is, then you can read, for example, in Wikipedia .
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Google Analitics uses mainly four types of cookies: __utma, __utmb, __utmc, __utmz (sometimes __utmv and __utmx occur, but during the crisis I didn’t feel the need to get them).
Let's sort each separately on an example.

__utma

These are the main user cookies that uniquely identify the site visitor and contain a lot of useful information about him.
These cookies last for two years (if the user doesn’t clear them), that is, you can receive information for a sufficiently long period of time.

Format: XXXX.DDDD.FFFF.PPPP.CC.N.
Example: 126394024.179004532335319200.1247654493.1260769004.1260878051.7

Values:

• XXXX - domain hash, does not contain useful information.
• DDDD is a unique user ID in Google Analytics.
• FFFF - the date of the first visit by the user of the site in Unix format (the number of seconds elapsed since January 1, 1970).
• PPPP - the date of the previous visit by the user of the site in Unix format.
• CCCC - the start time of the current visit (the beginning of the session) in Unix format.
• N - the number of visits to the site by this user.

__utmb

These cookies carry information about the current session of the user, the lifetime is 30 minutes after the last page viewed.

Format: XXXX.P.10.CCCC
Example: 126394024.1.10.1260878051

Values:

• XXXX - domain hash.
• P - the number of pages viewed by users during the current session.
• 10 - Google magic number is the same parameter on all sites, not changing over time. I think, does not carry useful information.
• CCCC - the time of the beginning of the current visit (the beginning of the session) in Unix format (similar to the CCCC parameter _utma).

__utmc

The lifetime of these cookies is the current session. Only contain domain hash.

__utmz

The most interesting of all cookies will tell you how the user came to the site, where he came from (if he used the link from another resource) and what keywords he searched for your site (if he came from a search engine).
Term life - 6 months, updated when loading the next page of the site.

Format: XXXX.TTTT.VSutmcsr {source} | utmccn {campaign} | utmcmd {medium} | utmctr {keyword}
Example: 126394024.1260524913.5.5.utmcsr = yandex | utmccn = (organic) | utmcmd = organic | utmctr = best

Values:

• XXXX - domain hash.
• TTTT is the date of the last cookie update in unix format.
• V - the number of visits by the user of the site made by links from other resources
• S - the number of different resources from which the user got to the site.
• utmcsr - search engine resource from which the user came to the site.
• utmccn - contains information about the company from AdWords (or the value utm_campaign in the request) or reports that the user got to you through organic search.
• utmcmd - contains the name of the company (or the value utm_medium in the request) or reports organic search.
• utmctr - keywords that were searched.

As you can see, these cookies contain a lot of useful information.
You can read more about Google Analytics Cookies in the official documentation .