How is a multilingual site indexed by robots?

Question

Search Engine Optimization

Hello, I asked myself:
there is a multilingual site that determines the visitor's preferred language and gives the visitor info. in his language. The language is determined from the client's browser settings.
But if a search robot (Yandex, Google) has entered, how do they indicate their preferred language?
If the robot specifically determines the language when indexing (for example, Russian), then how will it index the content of pages in another language (in English)?

Answer 1

No, in fact you should have pages with different URLs for each language, for example:

site.ru/ru/path/to/file
site.ru/uk/path/to/file
site.ru/en/path/to/file

Additionally, you need to:
1. Set the rel="canonical" attributes

<link rel="canonical" href="https://site.ru/ru/path/to/file"/>
<link rel="canonical" href="https://site.ru/uk/path/to/file"/>
<link rel="canonical" href="https://site.ru/en/path/to/file"/>

2. Set up automatic forwarding:
3. Enable the default language for Google and Yandex robots if they try to follow a link where the language code is not specified.
It can be assumed that everything should work according to this scheme , but, as practice shows, search engines ignore such markup.
PS If you don't redirect, the site.ru/path/to/file pages should always be displayed in the same language, otherwise they will be incorrectly indexed.

Answer 2

I suspect that from the point of view of the robot, the language versions of the site are 2 independent subsections of the site. And they are indexed independently.