The work of International Eucharistic Congresses began in France in 1881 and owed its inspiration to the efforts of leading Catholics of the time.
Over 8,000 people, including delegates from France, Chile, Greece and Mexico took part in the Lille congress.
There were 14 congresses between 1881 and 1902 during the pontificate of Leo XIII.
The sixth congress met in Paris in 1888 with the Church of the Sacred Heart on Montmartre at the centre of proceedings. The eighth congress took place in Jerusalem in 1893.
The first pope to chair a congress was Pius X in 1905 in Rome.
Around 30,000 children celebrated their First Holy Communion during the 21st Congress in Montreal in 1910.
Many congresses have been linked to anniversaries or other special events - the 30th Congress, which took place in Carthage in 1930, commemorated the 1,500th anniversary of the death of St Augustine.
The 31st Congress in Dublin in 1932, marked the 1,500 year anniversary of the arrival of St Patrick to the island.
The aim of the Eucharistic Congress, which normally takes place every four years, is to gather people together to promote an awareness of the central place of the Eucharist in the life and mission of the Catholic Church and draw attention to the social dimension of the Eucharist.
During the pontificate of Pope Pius XI, Eucharistic Congresses spread to countries outside Europe, including the US, Australia and Asia.
Following the congress of 1960, under the pontificate of John XXIII, the tradition of organising congresses on a four or five year basis was established.
Pope John Paul II chaired three congresses, in Nairobi in 1985, Seoul in 1989 and Seville in 1993.
Inter-religious relations were a feature in the Nairobi and Seoul congresses where the Pope addressed Hindus and Muslims in the former and held meetings with Buddhists and Confucians in Seoul.
Archbishop Piero Marini, President of the Pontifical Committee for International Eucharistic Congresses, said that every congress has a profound impact on the life of the church.
He said that because the 50th IEC coincides with the 50th anniversary of the opening of the Second Vatican Council, it can become “an important means of promoting an exemplary and fruitful celebration of the conciliar Liturgy”.
Archbishop Marini also said the IEC is not “a privilege bestowed on Dublin, but a service to the continuing journey of God’s People”.
The Pope convokes an IEC at a place proposed by a local bishop or Episcopal Conference.
However, bishops can also convoke diocesan or national Eucharistic conferences in their dioceses or respective countries.
Pope Benedict convoked the 50th IEC to be held in Dublin during his address to the 49th IEC in Quebec in 2008.
Eucharistic Congresses are organised by the Papal Committee for Eucharistic Congresses, which was established by priests and laity and confirmed by Pope Leo XIII in 1879.
It has also become the tradition that an international theological-pastoral symposium to be held around the time of the Congress.
The faculty of theology of the Pontifical University at St Patrick’s College Maynooth, will host the symposium on 6-9 June.
The symposium is aimed at participants who have at least a graduate level or equivalent in theology and will consist of plenary sessions, seminars and liturgies.
Papal Legate Cardinal Marc Ouellet gave the keynote address at the symposium’s formal opening on 6 June.
