State Cult

State Confucianism or Confucian State Cult was the main ideology that Imperial China (from 206 BCE-1912 with interruptions, some dynasties that pushed other ideologies) followed. The Confucian State Cult was deeply embedded into rulership and required the Chinese emperor to make sacrifices through rituals to Confucius and to Tian to legitimize their imperial authority and rule.

Veneration

Temples of Confucius or Wénmiào were built across the entire country where government officials did rituals to honor Confucius and his disciples. An example of the rituals conducted by the emperor is the Jì Kǒng or the Sacrifice to Confucius. This included the emperor to during spring and autumn to offer wine, silk and animal sacrifices (common are ox, sheep and pigs) and for the emperor to perform kowtows (kneel with your forehead touching the floor) infront of Confucius' spirit tablet as officials recites passages from the Confucian classics.

Qing and onward

With the Century of Humiliation where the ruling Qing dynasty was forced to bow down to Western powers, rebellions and efforts to modernize China State Confucianism saw a decline and practice of it stopped entirely after the Republic of China during the 1911 Revolution dropped Confucianism as state ideology.

Confucianism is still used today with the Chinese Communist Party, using the philosophy to justify and legitimize its rule (though it's used more culturally than politically, you won't spot the Secretary General of China bowing down to the spirit tablet of Confucius)