Overall this is my best picture. The depth-of-field is very strong, and the colors are vibrant. Placing the flower in middle works good for this photograph because it increases the effectiveness of the beauty of the flower. This is important because the flower is the main subject. Also the out-of-focus flowers in the background, makes this picture more dynamic. Field-of-depth is creating contrast between subject and background. It allows us to focus on subjects we intentionally want to standout.
Depth of field refers to focus. The depth of field in this photo is shallow, meaning that the range of focus is limited, not much is sharp. We do use depth of field to bring part of the picture to the attention of the viewer.