Wordology, Toast

The word toast derives from the Latin word 'tostare' (to scorch or roast). From Classical times it was common to flavor wine by floating small pieces of toasted bread in it. Sometimes these pieces would be flavored with spices; at other times the carbon in the toast would mellow the wine.

The following guidelines apply specifically to toasting in Canada and the United States.  Most people will lightly touch glasses when giving a toast, often saying "toast", "cheers" or a short phrase such as "to us". Toasting by raising the glass without touching is regarded by some as a slightly more sophisticated mode of behavior.
Except during formal occasions, it is not common to "propose a toast" in the more formal sense. However, when someone does make such a gesture, it is almost invariably met with approval regardless of the setting or the occasion.
If someone wants to propose another, this second toast should have a different focus than the first and be briefer than the first so as not upstage it. Subsequent toasts, if any, should even more succinct.

Americans and Canadians typically toast only once per gathering. Even lifting one's glass and saying "cheers" each time a new drink is poured is not impolite, but can get tedious.