Photosynthesis is quite a big word but broken down into two parts it is easy to see what it means. In Greek 'photo' means light and 'synthesis' is making something, or putting something together; "photosynthesis" is making something through light. Plants absorb the sun's energy through their leaves and convert it into food for themselves; this is called photosynthesis. As long as a plant gets carbon dioxide from the air, water (usually from the soil) and light from the sun, it has what it needs to survive.
In order for a plant or tree to undergo photosynthesis it needs to have leaves. The leaves contain everything needed to absorb the rays of the sun and allow photosynthesis to take place. The leaves are like tiny solar panels, all pointed towards the sun, soaking up its energy and converting it to practical food for the plant. Leaves absorb the raw materials needed for photosynthesis, carbon dioxide and water, and after the photosynthesis process the products of photosynthesis, sugar (glucose) and oxygen, leave through the leaf.
Light is the third element needed for the photosynthesis process after carbon dioxide and water. Light travels in waves from the sun, is absorbed into the earth's atmosphere and eventually strikes the plants, giving the energy needed for photosynthesis.
The light from the sun is absorbed by pigments in the leaves called chlorophyll. Chlorophyll is the substance that grabs the energy from the sun and starts the whole process of photosynthesis. It energises electrons in the leaves using specific wavelengths of light from the sun, allowing the creation of glucose and oxygen.
Photosynthesis occurs in stages. Water is collected from the roots and transferred through the plant to the leaves; at the same time, the leaves are absorbing carbon dioxide from the atmosphere. In the next stage, the leaves capture the sun's rays through the green chlorophyll pigments and stores the energy for later use. Eventually the process of photosynthesis converts the water to hydrogen and oxygen. The hydrogen is used as food for the plant and the oxygen is released into the atmosphere through the leaves.