My first exposure to the seriousness of “toasting” came from my time in the US Navy. The protocol and etiquette of “toasting” is even written in manuals; everything from the hierarchy of what and whom to toast to when to stand and even how to pass the wine/port.
“Toasting” to this day is evident in most aspects of life: state dinners, military events, weddings, company events, and private dinner parties, just to name a few. Today we use the ritual of the “toast” with wine, champagne, or fortified drink. Even if you don’t drink it is considered proper to participate in a toast by action without drinking the beverage.
The act of “toasting” has its roots in the 6th century BC. Historians agree that a piece of burnt bread (i.e. toast) was floated in a communal drink bowl to take the acid taste out of the wine/drink. Thus, it became known as a toast. The Greek and Romans used the ritual of a “toast” to honor their deity.
It became custom in later times to “toast” to health and happiness of friends and thus the word “cheers” was the shorthand word for best wishes. But, back to history.
Wine was also the beverage of choice to eliminate enemies, spouses or competition by poisoning. Poor quality wine made wine a convenient delivery system. To demonstrate that the wine was suitable for drinking the host would pour and drink the wine from the bottle being offered to guest to show that it was safe to drink.
A few theories exist about clinking glasses with a toast. One theory, possibly stemming from that Greek habit, is that by clinking glasses, you could slosh the poison someone may have put into your wine back into theirs. Another theory is that the sound of clinking glasses was thought to drive the evil spirits out of the spirits, making it safe to drink. Clinking could also be a way to make contact since we no longer all drink from the same bowl. Theory is that a good glass of wine or champagne appeals to the senses of sight, touch, taste and smell and, by clinking, it also appeals to the sense of sound, making it an all-encompassing sensual experience. (Etiquette International)