From The Art and Popular Culture Encyclopedia
A toast is a ritual in which a drink is taken as an expression of honor or goodwill. The term may be applied to the person or thing so honored, the drink taken, or the verbal expression accompanying the drink. Thus, a person could be "the toast of the evening", for whom someone "proposes a toast" to congratulate and for whom a third person "toasts" in agreement. The ritual forms the basis of the literary and performance genre, of which Mark Twain's "To the Babies" is a well-known example.
The toast as described here is rooted in Western culture, but certain cultures outside that sphere have their own traditions in which consuming a drink is connected with ideas of celebration and honor. While the physical and verbal ritual of the toast may be elaborate and formal, merely raising one's glass towards someone or something and then drinking is essentially a toast as well, the message being one of goodwill towards the person or thing indicated.