It is the process by which plants make food by which solar energy is trapped by auto tropic organism and converted into food for the rest of organisms. No other chemical process on earth can match the output by photosynthesis. It is interesting to note that only 0.2 percent of the light energy on earth is utilized by this process of photosynthesis.
Fossil fuels such as coal, petroleum, and natural gas are also product of photosynthetic organisms which lived million of years ago. Importantly it is the only natural process by which oxygen is liberated for use by other organisms.
Here is what happens during the process of photosynthesis
Photosynthesis is important for the world because it provides food and oxygen which are most important for human being and animals. Some of the glucose that plants produce during the process of photosynthesis is stored in fruits and roots. Thus we get apples, watermelons, potatoes and many more which are used in food. The oxygen produced during this process is released into the atmosphere. During the process carbon dioxide is also consumed which has bad effect on us. As such photosynthesis is very important for the world.