Here's some photo-ception for you. Depth of field is incredibly important for photographers to understand, so take a good look at this photo to get a sense of what depth of field is and how to use it in your photography. In this photo you can see the focal point of the photo is the camera in the photographer's hands, and the background has a nice blur to separate the camera from the walkway. Manipulating the depth in your photo is a instant way to make them look more professional. So how do you do that, you may ask? Adjust your aperture (measured in F/stop)! As a rule of thumb: the higher your F/stop, the smaller the opening in your lens and the greater depth of field. Lower F/stop means a wider lens opening, and a flatter photo overall. Now you can be a depth of field expert!
