How does searching work in Solr?

Question

Solr

On one project there is a search form, when you type in a query there, it refers to Solr and gives results from there.
I want to note right away that in Solr I am zero, so I want to understand what fields are being searched in Solr? Or are all fields affected, or for some specific one? For example, they are asked to make it clear why, on request, a slightly different info is given, as it got out of the solar (if the title of this document does not contain what was written in the search, but it is in some other field). For example, you write "Car Tires" and in addition to them, it also displays "Car Mirrors" in the search line (as I understand it, they get into the search, because in the Car Tires document there is an "additionally buy" field and the document "Car Mirrors" is included there Do I understand correctly?
And yet, where can I read and get acquainted with the solar? There is little normal material on the Internet for those who are not familiar with it, immediately for those who more or less understand

Answer 1

1) yes. According to a certain one or many
2) yes. But perhaps the system is stable in such a way that data from a completely different system is pumped to the results obtained.
3) here:

• https://lucene.apache.org/solr/
  
• www.solrtutorial.com/solr-in-5-minutes.html
  
• yonik.com/solr-tutorial
  
• www.solr-start.com