Hi John,
Yes like ''Hi,John" cause you pause a little when you say hi.
yes.....
you would only need to use a comma if you were writing a messege like this ex. Hi Mary, how are you? but if it was a conversation it could be Hi Mary ! ( or period)
Most greetings are considered interjections. Therefore, they are set apart from the sentence with either a comma or exclamation point. For example, "Hello! How are you today?" or "Hi, John."
Yes, a comma is typically used between a name and listing credentials. For example: John Smith, PhD.
The correct punctuation after the word "Hi" is usually a comma. For example: "Hi, how are you?"
The comma goes after.
you do not have to put the comma there
Comma after what?
Yes, you should put a comma after "welcome" when addressing someone by name. For example, you would write, "Welcome, John." The comma sets off the name from the rest of the sentence, following the rules of direct address in English grammar.
Traditionally, a colon for business letters and a comma for personal letters.
Do not put a space before a comma. Put one space afterthe comma.