Yesterday night as we had a dinner in a restaurant in Prague, Czech Republic, the waitress told us that there is an extra charge for the tip. If I am not mistaken of what I heard, she said 10% of the total bill. This is a form of gratuity but this is not voluntary because they have a certain amount that you need to pay depending on your bill.
Annuity on the other hand is totally different with gratuity. Don’t be confused with it. If I say immediate annuity, I am talking about financial contract that can also refer to life insurance. If you want to have an additional income when you retire, you can purchase a so-called life annuity. This is also a form of investment because somtime in the future you can withdraw a lump-sum from your series payments.