At this stage, the search for information is carried out directly according to users' search queries. First, the search engine analyzes the query, determines the weight of each keyword. Then it searches for matches according to inverted indexes, all documents in the search engine database that correspond to the search query are selected.
The document's compliance with the request is determined by a special formula:
similatiry(Q,D) = SUM(w qk * w dk ),
where similatiry(Q,D) is the similarity of query Q to document D ;
w qk — weight of the k-th word in the query;
w dk — weight of the k-th word in the document.
Documents that are most similar to the user's query are reflected in the search results.
Ranging
At the final stage, the search engine groups the cell phone database results so that the user sees links to the most relevant pages first. Each search engine has its own unique ranking formula, which takes into account the influence of the following parameters:
page weight (citation index, PageRank);
domain authority;
relevance of the text to the request;
relevance of external link texts to the request;
as well as many other ranking factors.
As an example, let's look at a simplified ranking formula:
R a (x) = (m * T a (x) + p * L a (x)) * F(PRa) ;
where Ra(x) is the final correspondence of document a to query x ;
Ta(x) - relevance of the text (code) of the document to the request x ;
Lа(x) — relevance of the text of links from other documents to document a for query x ;
PRа is the authority indicator of page a , a constant relative to x ;
F(PRa) is a monotonically non-decreasing function, and F(0) = 1 , we can assume that F(PRa) = (1 + q * PRa) ;
m , p , q are some coefficients.
Thus, the place of a page in search results is influenced by various factors that are both related to the search query and in no way connected with it.
The principle of operation of information retrieval systems: ranking criteria
If you want your Internet resource to be in the top three or at least ten search results, you need to know the principles of search engines and ranking criteria in order to constantly optimize the site to their requirements.
There are two main groups of such criteria:
Text search engine criteria.
In this case, the search engine ranks pages based on the quality of their text content. Optimization of this component of the site involves working with the semantic core at the stage of creating and filling the Internet resource.
The search engine, processing the user's request, will show the most relevant results on the first page of the results. In the process of searching for documents, the search engine analyzes the correctness of the title phrase (title), page description (description) and the presence of the key query in the headings (H1, H2, etc.).
Non-text search engine criteria.
The search engine carries out work on analyzing these criteria after the site is published and indexed. The main principle of ranking by the criteria of this group is to evaluate not the quality of their content, but the external link profile.
The search engine analyzes the number of links to the site from other Internet resources, evaluates their authority, looks at registrations in directories. If we draw an analogy, then the search engine, like a bank that decides to issue a loan to a company, collects reviews about it from counterparties, suppliers, and other creditors.
Knowing how search engines work will help you create and optimize websites that will easily occupy the top positions in search results and stay there for a long time, since they correspond to users' search queries.