Rice is a special plant. It grows best with its roots sitting in shallow water. So if you want to grow rice on a steep hill, you can't just plant seeds - the water would run straight down. Instead, farmers cut the hill into flat ledges, one above the other, with small walls of earth around each one to hold the water in.
Some terraces in Vietnam are hundreds of years old. They were built by families using simple wooden and metal tools, working together over many generations. The most famous ones are around Sa Pa and Mu Cang Chai, where the steps climb up the mountains like the rungs of a ladder.
Each season the terraces change colour. In spring they shine like mirrors when the fields are flooded with water. In summer they turn bright green as the rice grows. In autumn the rice turns gold, just before harvest. In winter, the empty fields rest until the next year.
Rice is Vietnam's most important crop. The country grows so much that it sends rice to families all over the world. The grains we cook in our homes from a packet might have started life on a hillside in Vietnam.