There are a variety of understandings of Holy Communion within the Christian Church.
Even the names used vary between churches: Holy Communion, The Mass, The Lord's Supper, The Eucharist...
However the service and practices are understood, the overarching story is that of Jesus at the Last Supper, "This is my body..."
Many denominations have been on a journey over the second half of the last century and now offer children the bread and wine. In many churches it is an on-going discussion:
Should children be offered Communion and at what age?
What, if any, understanding do children need before they are allowed to receive?
What is the relationship between Holy Communion and belonging to the Church Family?
How far is receiving Holy Communion experiential rather than cerebral?
How does our understanding of Holy Communion affect our inclusion of children in the service?