Russian grammar encompasses:

• a highly synthetic
  Synthetic language
  In linguistic typology, a synthetic language is a language with a high morpheme-per-word ratio, as opposed to a low morpheme-per-word ratio in what is described as an isolating language...
  
   morphology
  Morphology (linguistics)
  In linguistics, morphology is the identification, analysis and description, in a language, of the structure of morphemes and other linguistic units, such as words, affixes, parts of speech, intonation/stress, or implied context...
  
  
• a syntax that, for the literary language, is the conscious fusion of three elements:
  • a Church Slavonic inheritance;
  • a Western Europe
    Western Europe
    Western Europe is a loose term for the collection of countries in the western most region of the European continents, though this definition is context-dependent and carries cultural and political connotations. One definition describes Western Europe as a geographic entity—the region lying in the...
    
    an style;
  • a polished vernacular
    Vernacular
    A vernacular is the native language or native dialect of a specific population, as opposed to a language of wider communication that is not native to the population, such as a national language or lingua franca.- Etymology :The term is not a recent one...
    
     foundation.

The Russian language

Russian language

Russian is a Slavic language used primarily in Russia, Belarus, Uzbekistan, Kazakhstan, Tajikistan and Kyrgyzstan. It is an unofficial but widely spoken language in Ukraine, Moldova, Latvia, Turkmenistan and Estonia and, to a lesser extent, the other countries that were once constituent republics...

 has preserved an Indo-European

Indo-European languages

The Indo-European languages are a family of several hundred related languages and dialects, including most major current languages of Europe, the Iranian plateau, and South Asia and also historically predominant in Anatolia...

 synthetic

Synthetic language

In linguistic typology, a synthetic language is a language with a high morpheme-per-word ratio, as opposed to a low morpheme-per-word ratio in what is described as an isolating language...

-inflexional

Inflection

In grammar, inflection or inflexion is the modification of a word to express different grammatical categories such as tense, grammatical mood, grammatical voice, aspect, person, number, gender and case...

 structure, although considerable levelling has taken place.

The spoken language has been influenced by the literary, but continues to preserve characteristic forms. The dialects show various non-standard grammatical features, some of which are archaisms or descendants of old forms since discarded by the literary language.

NOTE: In the discussion below, various terms are used in the meaning they have in the standard Russian discussions of historical grammar.