One is ready-to-eat food, such as cakes, bread, steamed bread, oil cakes, fried dough sticks, glutinous rice balls, jiaozi, wonton and so on. Generally, you can eat it when you buy it, each with its own characteristics.
Second, all kinds of quick-frozen foods are prepared in advance, then frozen in containers and eaten after a little heating.
The third kind is dry or powdery instant food, which can be eaten after being brewed with water or boiling water, and made into instant noodles, instant rice noodles, instant rice, instant drinks or seasonings, instant milk powder, etc.
The fourth kind is canned food, that is, a kind of canned food with film instead of metal and glass bottles. This kind of food keeps the original flavor of the food well, and it is small in size, light in weight, hygienic and convenient, but the price is slightly higher.
There are also some semi-finished foods, which can be regarded as convenience foods.