In this video from clickherephotography we learn how to take great photos by using depth of field. In a picture of a bird he used an aperture of about 5.6 which increased the shutter speed on a 300mm Canon lens. With depth of field you can blow your background out. If you used a higher aperture, a lot more of the bird would have been in focus and a bit of the background would have been in focus. By using an F-stop and this aperture, you really bring the bird or whatever object is in the foreground into focus. Using a wide aperture or F stop to take photographs blows out the background. In a landscape photo he took, by using a slow shudder speed, anything the moves is recorded as a blur.