Visitors from other Christian groups to an Orthodox Divine Liturgy will often find some similarities to their own religious services along with some major differences. For example, visitors from other liturgical Churches will recognize the Epistle and Gospel readings, the Alleluia, and the Anaphora or Canon before the distribution of the Eucharist. One major difference, however, is the Orthodox belief that there is no minimum age requirement for the reception of Holy Communion. Orthodox children, including infants, who have been Baptized and Chrismated (Confirmed), are welcome at the Lord’s Table.
For example, here is a video of an Orthodox infant, who having just been Baptized and Chrismated (Confirmed), receiving Holy Communion.
This is quite different from the Christian West. In Roman Catholic theology, for example, there is an emphasis on children understanding what the Eucharist means before they are permitted to receive the Eucharist. Most Protestant Christians have inherited this viewpoint. However, historically, this restrictive view that infants and children should not be welcomed to the Lord’s Table only developed in the Western Church and dates only from about 800 years ago. All the Christian Churches of the East (including Coptic, Armenian, Syrian, Byzantine Orthodox, etc.) have maintained the earlier tradition of giving the Eucharist to infants as well as adults. In fact, infant Communion was also practiced as a norm in the West up until about 1200 A.D.
St. Augustine of Hippo bears testimony to the practice in the Western Church of infants receiving from the Lord’s Table:
“Those who say that infancy has nothing in it for Jesus to save, are denying that Christ is Jesus for all believing infants. Those, I repeat, who say that infancy has nothing in it for Jesus to save, are saying nothing else than that for believing infants, infants that is who have been baptized in Christ, Christ the Lord is not Jesus. After all, what is Jesus? Jesus means Savior. Jesus is the Savior. Those whom he doesn’t save, having nothing to save in them, well for them he isn’t Jesus. Well now, if you can tolerate the idea that Christ is not Jesus for some persons who have been baptized, then I’m not sure your faith can be recognized as according with the sound rule. Yes, they’re infants, but they are his members. They’re infants, but they receive his sacraments. They are infants, but they share in his table, in order to have life in themselves” (Augustine, Sermon 174, 7).
Fr. Robert Taft, S.J . (who was on the faculty of the Pontifical Oriental Institute  in Rome) explains about the history of infant Communion in the Western Church in an article entitled “Liturgy in the Life of the Church”  :
“The practice [of communing infants] began to be called into question in the 12th century not because of any argument about the need to have attained the “age of reason” (aetus discretionis) to communicate. Rather, the fear of profanation of the Host if the child could not swallow it led to giving the Precious Blood only. And then the forbidding of the chalice to the laity in the West led automatically to the disappearance of infant Communion, too. This was not the result of any pastoral or theological reasoning. When the Fourth Lateran Council (1215) ordered yearly confession and Communion for those who have reached the “age of reason” (annos discretionis), it was not affirming this age as a requirement for reception of the Eucharist.
“Nevertheless, the notion eventually took hold that Communion could not be received until the age of reason, even though infant Communion in the Latin rite continued in some parts of the West until the 16th century. Though the Fathers of Trent (Session XXI,4) denied the necessity of infant Communion, they refused to agree with those who said it was useless and inefficacious — realizing undoubtedly that the exact same arguments used against infant Communion could also be used against infant baptism, because for over ten centuries in the West, the same theology was used to justify both! For the Byzantine rite, on December 23, 1534, Paul III explicitly confirmed the Italo-Albanian custom of administering Communion to infants….So the plain facts of history show that for 1200 years the universal practice of the entire Church of East and West was to communicate infants. Hence, to advance doctrinal arguments against infant Communion is to assert that the sacramental teaching and practice of the Roman Church was in error for 1200 years. Infant Communion was not only permitted in the Roman Church, at one time the supreme magisterium taught that it was necessary for salvation. In the Latin Church the practice was not suppressed by any doctrinal or pastoral decision, but simply died out. Only later, in the 13th century, was the ‘age of reason’ theory advanced to support the innovation of baptizing infants without also giving them Communion. So the “age of reason” requirement for Communion is a medieval Western pastoral innovation, not a doctrinal argument. And the true ancient tradition of the whole Catholic Church is to give Communion to infants. Present Latin usage is a medieval innovation” (emphasis added) (Text from here ).
Eastern Catholics (those Catholics which celebrate other liturgies such as the Byzantine, Armenian, Coptic or Syrian liturgy) generally adopted the later Roman practice of delaying communion until “the age of reason” once they entered union with Rome (1500 – 1700s A.D.) and thus discontinued infant Communion. This is explained by Pope Benedict XIV’s encylical Allatae Sunt (On the Observance of the Oriental Rites) , given 26 July 1755. First, Pope Benedict XIV explains that:
24. For several centuries the practice prevailed in the Church of giving children the Eucharist after the sacrament of baptism….For the last four centuries, the Western church has not given the Eucharist to children after baptism. But it must be admitted that the Rituals of the Oriental churches contain a rite of Communion for children after baptism. Assemanus the Younger (Codicis Liturgici), bk. 2, p. 149) gives the ceremony of conferring baptism among the Melchites. On page 309, he quotes the Syrians’ baptismal ceremony as it was published by Philoxenus, the Monophysite Bishop of Mabbug, and on p. 306, the ceremony from the ancient Ritual of Severus, Patriarch of Antioch and leader of the Monophysites. He gives also the ceremonies of baptism observed by the Armenians and Copts (bk. 3, p. 95 and 130). All of these ceremonies command that the Eucharist should be given to children after baptism.
Here, Pope Benedict XIV dates the time the Latin Church stopped giving the Eucharist to children to 400 years earlier — in the 1300s. He recounts how the practice of the Eastern Church still gave testimony to Infant Communion and then notes the various Eastern Catholic synods which stopped the practice in imitation of the Latin Church from the 1500s to the 1700s. The specifics of the removal of Infant Communion can be read in the link to Pope Benedict XIV’s encyclical above. Eastern Orthodox Christians maintained the historic tradition, however.
However, in the past 15 years or so various Eastern Catholic Churches have started to restore infant Communion with encouragement from Rome. The first indication of this was in 1990 with the publication of the Code of Canons of the Eastern Churches  (Eastern Catholic Canon Law). Canon 710 of that law stated:
With respect to the participation of infants in the Divine Eucharist after baptism and chrismation with holy myron, the prescriptions of the liturgical books of each Church sui iuris are to be observed with the suitable due precautions.
“In the Eastern rites the Christian initiation of infants also begins with Baptism followed immediately by Confirmation and the Eucharist…” (Section 1233)
However, there is no uniform practice yet among Eastern Catholics on infant Communion. When my two children were Baptized and Chrismated (Confirmed) in the Ruthenian Byzantine Catholic Church in 1994 (ages 5 and 3), they were the first children in our Eparchy (Diocese) to receive the Eucharist at the time of their Baptism/Chrismation. The Ukrainian Catholic Church decided in 1997  to begin the restoration of infant Communion. Some parishes have implemented the change, but many have not. The tradition of “First Communion” dies hard in some places. The Melkite Greek Catholics (also in union with Rome) have generally restored infant Communion. According to this source , this has happened since about 1969, but many parishes have retained a “First Solemn Communion” that reflects the “First Communion” experience from the Latin Church.
The vast majority of Protestant churches do not practice infant Communion, though a few Protestant churches  do practice or tolerate it. It enjoys limited support by some Reformed writers  and has been debated in the Episcopal Church. It has also become an issue for several Lutherans  who are contemplating converting to Orthodoxy. Some Lutheran writers have also correctly noted that the discontinuance of the practice of communing infants in the Western Church  dates from about the twelfth century. Since 1997 , some parishes  of the Evangelical Lutheran Church in America (ELCA) now practice infant Communion.
Meanwhile, the Orthodox Christian East has retained this ancient tradition of the undivided Church of the first millennium.