I only really know how it works in my denomination, which is Roman Catholic. In Roman Catholicism, you can partake at the Eucharist very frequently (at daily Mass) and it is considered to (after the priest blesses the bread and wine) to be the actual Body and Blood of Jesus Christ, through transubstantiation. (Don't ask me to explain how that works, I'm still not sure tbh
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I believe we are the only denomination that believes in transubstantiation. If you have not been baptised and done your First Holy Communion ceremony, then you should not be partaking in the Roman Catholic Eucharistic celebrations, in terms of receiving the transformed bread and wine. Roman Catholicism is very strict about who can and cannot receive the bread and wine. So the answer to your first question about what to do with it when given it, is - don't go up to get it
As I've said, in Roman Catholicism it is taken to be the actual Body and Blood of Jesus Christ, after transubstantiation. In most (if not every) other denominations, it is understood to be a memorial act in remembrance of the Last Supper. It is not taken to be the Body and Blood of Jesus. Communion in these denominations may be infrequent (monthly, I think in Baptist churches) or not even done at all (Quakers).
Hope this helps a bit. Why do you ask?