This principle is that resources are selected for display on the relevance of the text content of a user request. That if there is text resource contains the maximum number of matches to a query, a reference to this resource and will be the first among the displayed as search results. There are other, less important and more difficult to understanding the mechanisms of search engines. However, the principle of contextual relevancy is the absence to date of other significant resources, a priority. Service Yandex is a leading, if not leadership, service provider, along with other world-class services services of Internet search. Many users search for and find the resources they need through the service. The principles of contextual advertising system Yandex generally similar to the universal principles of contextual advertising, but there are several more specific features of the system, which the advertiser should also be taken into account.
The more diverse set of terms, the more chance of getting accurate that is likely to increase the rating of a link to the advertiser in the list of results displayed. In addition, you should consider writing and accuracy of the term, although it is accurate, as shown below, can be quite unusual form. Set of terms used for contextual advertising in professional language called "keywords", "of keywords" or just "key" can be extended in various ways. One of them – the use of synonyms, and clarifying terms. For example, together with the term "home electronics" can be used the term "home audio equipment," or "sale electronics.