The descent of the Holy Spirit upon the Apostles fifty days after Pascha, marking the full revelation of the Holy Trinity and the beginning of the Church's mission in the world. During Vespers, special kneeling prayers are offered and the church is adorned with greenery. This feast celebrates the completion of Christ's saving work and the outpouring of the Holy Spirit upon all believers. From this day forward, the Sundays of the year are numbered from Pentecost, signifying the continual life and growth of the Church in the grace of the Spirit.

The central worship service of the Orthodox Church, celebrating the Eucharist (Holy Communion). Usually celebrated on Sundays and feast days, the Divine Liturgy consists of the Liturgy of the Word (scripture readings) and Liturgy of the Faithful (Eucharistic prayer and communion). The most common forms are the Liturgies of St. John Chrysostom and St. Basil the Great.

Brief prayer services traditionally celebrated at specific times of day: First Hour (6 AM), Third Hour (9 AM), Sixth Hour (noon), and Ninth Hour (3 PM). Each Hour includes psalms, troparia, and prayers appropriate to that time of day. These services sanctify the day and connect us to Christ's Passion, as they commemorate specific moments in His crucifixion and death.

The missionary bishop who translated the liturgy and scriptures into native Alaskan languages. Celebrated on March 31st, Innocent (John Veniaminov) served as a priest and later bishop in Alaska and Siberia. He learned multiple native languages and created alphabets for languages that had none, earning him the title 'Apostle to America.'

The Patriarch of Moscow who led the Russian Orthodox Church through the Communist persecution. Celebrated on April 7th, Tikhon was elected Patriarch in 1917 and courageously opposed Soviet attempts to control the Church. He defended Orthodox faith and clergy during the most difficult period of Russian Church history. He represents faithful leadership under persecution.

A devotional service of praise consisting of hymns sung while standing ("akathist" means "not sitting"). The most famous is the Akathist to the Theotokos, traditionally sung during the fifth Friday of Great Lent. Akathists can honor Christ, the Theotokos, or various saints. These services are deeply moving expressions of Orthodox hymnography and devotion.

The spiritual fathers of Optina Monastery who renewed Russian monasticism and spiritual direction. Celebrated on October 11th, these elders (including Sts. Moses, Anthony, Hilarion, Macarius, and Ambrose) guided thousands of pilgrims from all walks of life. Writers like Dostoevsky and Tolstoy sought their counsel. They represent the flowering of Orthodox spiritual guidance in 19th century Russia.

The sacrament of marriage, uniting a man and woman in lifelong union blessed by God. The Orthodox wedding service consists of two parts: the Betrothal (exchange of rings) and the Crowning (placement of crowns on the couple's heads). The crowns symbolize both the glory and martyrdom of marriage, as well as the couple's status as king and queen of their domestic church. The couple drinks from the common cup and processes around the analogion three times. Marriage is understood as an icon of Christ's union with the Church.

The sacrament of initiation into the Orthodox Church, through which a person is united with Christ in His death and resurrection. The baptismal candidate is immersed three times in water in the name of the Father, Son, and Holy Spirit, dying to sin and rising to new life in Christ. Baptism cleanses from original sin, grants adoption as God's child, and makes the person a member of the Body of Christ. In Orthodox practice, baptism is immediately followed by chrismation and first communion.

The first Bishop of Jerusalem and author of the Epistle of James, called 'the Just' for his righteousness. Celebrated on October 23rd, James was a 'brother' (relative) of Jesus who became leader of the Jerusalem church after Christ's ascension. He was martyred by being thrown from the Temple. He represents Jewish Christianity and the transition from Judaism to the Church.

A miraculous icon of the Theotokos known for comforting the afflicted and healing the sick. Celebrated on November 6th, this icon shows the Virgin Mary surrounded by angels distributing aid to various people in distress. Many miracles have been attributed to prayer before this icon, especially healing from illness and comfort in grief.

The soldier-saint of Thessalonica, martyred under Galerius around 306 AD. Celebrated on October 26th, Demetrius is patron of Thessalonica and soldiers. Myrrh flows from his relics, earning him the title 'Myrrh-Streamer.' He represents faithfulness unto death and divine protection of Christian communities.

The first priest martyred by the Bolsheviks, shot while returning from church in 1917. Celebrated on October 31st, John served parishes in America before returning to Russia where he was killed for his faith. He was the first of thousands of clergy martyred during Communist persecution and represents the beginning of the New Martyrs period.