The world of restaurant dining requires certain things from an etiquette point of view. There are many of them and gratuities are one of these etiquette tangos has to do with.
There is also a general rule that concerns this. It is to leave a gratuity of 10-15% of the total bill for good service. For this reason wait staff often try to add to the amount of your bill by suggesting appetizers, desserts, or pricey alcoholic beverages. And that is the bigger the amount of the bill, the bigger the amount they expect to receive.
It is important for everybody to be served good. A good service includes promptness and attentiveness to your needs. They should pay attention to detail and get your order and particular requests correct. Moreover, they should bring drink refills promptly and efficiently and be friendly and know the menu, being able to suggest options.
Nevertheless, the wait staff should not be punished for things they have no control over. This means that if food is not cooked as desired, or takes longer than normal, the wait staff shouldn't be blamed. Neither is the condition of the bathrooms or how long it takes for you get seated. It is not the fault of the waiter or waitress even though these contribute to the overall dining experience.
The waiter or waitress keeps the entire tip in some restaurants. But the other establishments either require or recommend that the tip is shared with other employees - such as the bartender, cook, or bus boy. But there are places, where tip-sharing is only a recommendation. It is a guarantee there that the wait staff who industriously splits the tip with other employees will get their drinks made quicker, tables bussed cleaner, and food prepared with more assiduousness.
But there is also another issue and this is bad service. Of course, it will be reflected in the tip you leave. If the server is inattentive, rude it will cause you to have a negative experience. There are some ways to go about showing your discontent with the service. And in this case you will leave only a dollar or two. But you also can leave nothing at all. Moreover, it is also said that a penny left tail side up on a table is a sign of bad service.
If your food was superb then you may send compliments to the chef. Let the manager know in case your waiter or waitress left something to be desired, but you really enjoyed the taste of the food or the atmosphere of the restaurant. You can also ask if you can leave a tip for a waiter or waitress if he or she was specially helpful. Planning to return, you may want to make certain that you get good service the next time around.