It is a custom during special events such as weddings and holiday parties to raise a toast. We think of it as a bonding ritual to drink in hunison. But why is it called a "toast'? There's more than one theory about this, one of which is quite literal. At one time, a bowl of punch or grog would be garnished with toasted bread floating on top.
Although it now seems strange, for the privileged in medieval Europe, no day was complete without a bowl of warm wine and “sop,” sodden, toasted bread. Even Joan of Arc was known to enjoy it. For everyone else, warm, ale-soaked bread was an inexpensive, calorie-filled meal. But sops were added to soup and milk as well. Toasted bread was a potent symbol of plenty. The English even covered apple trees in cider-dipped toast, as part of an ancient ritual for a good harvest. (The custom is still ongoing.)
Read about the custom of drinking a toast with actual toast at Atlas Obscura.
(Image source: Wellcome Collection)