Since the earliest of times, the ancient Slavic calendar was called "lunoslov" and contained the original names of the “colorok” months. The Slavic calendar was a solar one, based on four seasons, each marked by a solstice celebration: June 20 — summer solstice, September 22 — autumn equinox, December 21 — Koliada, god of the newborn infant sun, March 20 — spring equinox.
The word "calendar" appeared in Russia only at the end of the 17th century, during the reign of Peter the Great. Despite the new name, its functions remain the same — fixing dates and measuring time intervals. The calendar allows us to record events in their chronological order, and is designed to highlight special days — like holidays.