Light can come from many directions and that greatly affects color, shape, and texture. Let us look at the four basic directions and how it relates to photography.
Front Light: The light illuminates the front of the subject. Shadows are washed away and can give the photograph a flat appearance. But it is good for color and details and if you are careful with the selection of the background, you can create an interesting picture.
Side Light: The light illuminates the subject from the side. It created strong shadows, adds texture, supports brilliant color, and adds depth to the picture.
3/4 Light: The light illuminates the subject halfway between side and back lighting. It shows detail, definition, and puts emphasis on depth.
Back Light: The light illuminates the subject from behind. It can create a halo effect around the subject. This light can create strong silhouettes.
Now all this seems pretty basic, but it is surprising how many people just fail to see how the light falls on their subject and that if they were to move a few meters one way or another, they could greatly improve their photographs.