An aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. The aperture stop of a photographic lens can be adjusted to control the amount of light reaching the film or image sensor. In combination with variation of shutter speed, the aperture size will regulate the film's or image sensor's degree of exposure to light.
Shallow Depth of Field
Medium Depth of Field
Deep Depth of Field
Best picture
This is my best picture because it clearly shows aperture. This image shows the correct white balance, iso and exposure.
Worst picture
This is my worst picture because it doesn't show aperture. I was hoping for it to focus on the flower only, It is also quite boring. To improve it could change the angle and the aperture.