When taking a photograph, it is important to position the image as best you can. This way it is not as hard to crop in the darkroom during printing. This means you also need to know how to position your subject correctly. One way to position your subject is by using the rule of thirds. Say you have a piece of paper that has three columns and 3 rows.
If you want to take a picture of an orange, imagine placing it in one of the white boxes in the square. This example will teach you how to place the subject using the rule of thirds and keep you from placing subjects dead in the center.
When taking a photograph, you need to decide where your objects belong according to their position. Take the picture of this stone lion for example. The eyes of the lion are looking off to the right; thus the photographer left negative space in that direction. The lion itself is called positive space because it is where the subject is placed, and the space left open is called negative space because the area is unused.
