Every cultural person at a meeting withfriends and friends should say "Hello." Thus he welcomes them. It is customary for the military to say "I wish you good health". These expressions have a common origin. Other languages also have similar words. For example, the Latin "vivat".
What is "vivat" in Latin? In translation, it means "long live". In Russia this word became widespread in the eighteenth century. This expression is usually used as a wish for prosperity and success. It is considered obsolete, but some people still use it often in their vocabulary.
However, Peter the First disapproved of theto the given expression (hurray). In some sources it is reported that the emperor even banned the use of it at all on pain of death. He considered such a call inappropriate, spreading panic in the ranks of the fighters.
Instead of "hurray" Peter proposed to introduce "vivat". This made the Russian army similar to the European one. After a while, the word began to greet not only the commanders, but also the royal family. Then the expression of a long period was used widely enough. At the moment it is less common.
Thus, we got an answer to the question about what "vivat" is. This is a magnificent greeting, and a wish for health, and an analogue to the cry of "hurray."