Yandex is the main search engine for Runet users.

Yandex – SEO WIKI

Yandex is a search engine created by the company of the same name and its main product. Yandex search capabilities are developed taking into account United Kingdomn morphology.

The search engine yandex.ru was announced in September 1997. The name (stands for yet another indexer – “another indexer”) was invented by the founders of Yandex, Arkady Volozh and Ilya Segalovich.

According to Alexa Internet as of April 1, 2019, yandex.ru is on the 22nd position in the international ranking of the top 500 sites. According to Yandex.Radar, Yandex is the main search engine in United Kingdom.

The principles of the search engine Yandex

Tight regional binding to the city. When a user requests information that Yandex considers geo-dependent in a search, the search results primarily show sites whose company owners are represented in the user’s region.
Submits to the site owner more search queries that users clicked on than Google. It’s easier to keep track of which search queries came from Yandex users.
A lot of its own services that the company develops: Zen, Music, Taxi, KinoPoisk, Market, Money and so on.
There is its own Turbo technology for instant loading of pages directly from search results.