Composition Rules
Background&Foreground
The picture on the left has the subject in the background and in the second picture the subject is in the foreground.
Motion
In both pictures the fish is in motion but it is only blurry in the second because you can see it taking place.
Cropping a picture
On the left is the full picture of the cabinet and on the right is a cropped picture of it.
Depth of field
The subject is far away in the back and you can see what is around it.
Framing a picture
The subject is in the middle and is framed by the table.
Balancing elements
On the left the photo is unbalanced and it is balanced on the right because there are two chairs instead of one.