Usually, leaves change its color during the season of winter and fall from green to yellow, orange and red. Trees makes the use of the process called “photosynthesis” in the making of the food and energy and this process happens due to the pigment present in leaves called “chlorophyll”. So whenever the season of the fall and winter comes, the green color of the chlorophyll begins to fade away as there is not much sunlight and water for the photosynthesis to occur. So the green color of the leaves disappears.