Today, "Chinese food" in China remains primarily local and regional dishes rule what's served in most restaurants and homes. However, due to a large number of Chinese immigrants, there are dozens of adaptations of "Chinese food," particularly in immigrant countries like the United States, Canada, & the United Kingdom.
Staple Foods
Rice: served with nearly every meal in the south, but not as popular in the north
Noodles: more commonly served in the north; often made of wheat, soy, or rice, although additional varieties exist
Dumplings: more common in the north, often when dumplings are served, other starches, like noodles, are not
Regional Variations, Specialties, & Unique Dishes
Beijing: Beijing's most famous dish (although not its most popular) is Peking Duck
Hong Kong: dim sum are small dishes so each person can try various foods at one meal; the ingredients and cooking styles of each varies widely
Sichuan: this area is known for their hot and spicy foods
Dining Etiquette
If you're from a culture that uses forks and knives be prepared for what may seem like "food chaos." Dining etiquette, habits, and customs in China will at first seem very odd, and perhaps even rude, however the meanings and reasoning behind their actions will help you understand how to eat in China.
As you sit down to dine, you'll be greeted by little more than chopsticks, a spoon, a saucer, and a welcoming host. Hopefully not too welcoming, since fish eyes are a delicacy reserved for guests of honor or the oldest male of each generation. If you're served these, it's rude to turn them down. The chopsticks are obviously for eating (never place these sticking up in the rice, it's a sign of death); most locals will understand if you request a fork and knife. The spoon is for the soup, and the saucer is a "discard tray" of sorts; reserved for bones and shells that you pick out of your food.
When the meal arrives, the dishes (including the soup) are placed in the middle of the table. Generally tea is also served and you may notice most locals will actually poor the hot tea over their chopsticks and other eating utensils, into a bowl. This is done in fear of the eating utensils being contaminated and hence the boiled tea will cleanse them. Generally speaking, this is an unnecessary step, but if you are with locals taking part, join in the ritual. Eating begins in order of honor so don't begin until you're directed to do so by your host. Also, don't fill up on the main course since, later in the meal, each person will receive his or her own bowl of starch, typically rice or noodles and this is the most important dish.
As you eat the soup, suck it into your mouth so you make a slurping sound; this will cool the soup and all locals use this technique to prevent burning. The food shall be picked at with your chopsticks and eaten directly from the communal plates, as will the soup. If one of those dishes is fish, don't flip the fish over (locals believe it will flip over the boat of the fishermen).
When the starch arrives, you should pick up the entire bowl and shovel it into your mouth bite by bite if eating in a home; not picking up your bowl is a sign that the food was unsatisfactory. Also, leaving any of the starch behind is considered an insult to the workers who farmed it. When finished, join the locals with a tooth pick in hand to clean any remaining food from your teeth.
Most Chinese will order only as much food as is needed, however for business dinners or for celebrations, an excess of food should be ordered and the number of dishes ordered must always be even.
In general there is no tipping in China; however there are a couple exceptions. Hong Kong, and to a lesser degree Macau tip more often since they were under foreign rule for so many years. Generally, restaurants in these cities will add 10% service charge to their bills. If no service charge was added, you may tip 5-10%, although this is by no means necessary. No other restaurants in China expect tips.
Celebrations & Events
A number of festivals in China are associated with varying foods, most particularly the Spring Festival, Dragon Boat Festival, Mid-autumn Festival, and the Lantern Festival. At the Spring Festival tangyuan (rice balls filled with nuts, bean paste, and more) is the food of choice and an essential part of this celebration.
The Dragon Boat Festival has a larger number of traditional foods and this begins with zongzi, which are rice dumplings wrapped in leaves filled with anything from meat to fruit. Other popular foods during this festival include mianshanzi (flour shaped into a fan), jiandui (fried cake), eel, eggs with garlic or tea, and pancakes (like crepes).
During the Mid-autumn Festival moon cakes are the most common food. These cakes are always filled with something, generally fruit, sugar, beans, ham, or cream. The Lantern Festival generally serves tangyuan and yuanxiao, which is similar to tangyuan.
Drinks
Although water in China is best approached with caution, the country's most common drink, tea, uses the water after being boiled. Tea is drunk daily by most people and, although it can be served with food, it is more commonly served with snacks, dim sum, or alone. When someone fills your tea glass, tapping the table with two fingers is a way of saying "thank you." Coffee is quickly growing in popularity, especially in the big cities. Additionally, all popular international beverages can be found in the country, from milk and juice to soft drinks and others.
Rice wine is popular in China and beer is growing in influence as well. These are the most popularly produced alcoholic beverages in the country, but imports are also common, particularly in Hong Kong, where nearly every international brand can be found.
The tap water in China should not be consumed because in most places it is not safe. Be sure to also avoid anything with ice as it may have been made from the tap water. Salads and fruits may have also been washed in the tap water so be careful with those foods as well.