In the context of Russian Orthodox church history, the Old Believers (Starovery, Russian: старове́ры or старообря́дцы) separated after 1666 from the official Russian Orthodox Church as a protest against church reforms introduced by Patriarch Nikon between 1652–66. Old Believers continue liturgical practices which the Russian Orthodox Church maintained before the implementation of these reforms.

Russian-speakers refer to the schism itself as raskol (Russian: раскол), etymologically indicating a "cleaving-apart".

In 1652, Nikon (1605–81; Patriarch of the Russian Orthodox Church from 1652 to 1658) introduced a number of ritual and textual revisions with the aim of achieving uniformity between Russian and Greek Orthodox practices. Nikon, having noticed discrepancies between Russian and Greek rites and texts, ordered an adjustment of the Russian rites to align with the Greek ones of his time. In doing so, Nikon acted without adequate consultation with the clergy and without gathering a council. After the implementation of these revisions, the Church anathematized and suppressed—with the support of Muscovite state power—the prior liturgical rite itself, as well as those who were reluctant to pass to the revised rite. Those who maintained fidelity to the existing rite endured severe persecutions from the end of the 17th century until the beginning of the 20th century as schismatics (raskol'niki, Russian: раскольники). They became known as "Old Ritualists" (staroobryadtsy), a name introduced during the reign of Empress Catherine the Great. They continued to call themselves simply Orthodox Christians.