Greetings: what the textbook forgets to tell you

It’s "Salut" not "Bonjour" when you walk back in from lunch. Sort of the English equivalent of Hey rather than Hello.

And so hello, or "Bonjour" can be used for the morning. "A tout" (the shortened form of "a tout a l’heure" or see you later) for before lunch-- and only if you’re actually seeing the person within the next hour. They use "Salut" for after lunch. And either the formal "Au Revoir" for the end of the workday, or "A Demain" (until tomorrow) if you’re all friendly, colleagues, the like.

It’s the little things you learn when out of grammar class and immersed into the everyday environment-- the common, workplace conversation. I understand French fluently, thanks to my Mother having spoken to me in French until I turned 17. But to keep up with the fast pace at which Parisians speak up-- it's difficult. And to pick up on the slang and jokes, that I wouldn't understand even if they were in English-- that I find hard too. 

But it’s good being around it. Because that's the way you learn.