Focus - Soft Focus
By using a soft focus lens or some semi/transparent device in front of the lens, like a filter with smears of Vaseline, nose oil or vegetable oil on it, that breaks the light up, the whole image can be made to take on a soft focus aesthetic where no one area of the image is in sharp focus.
By experimenting with smearing on the diffusing substance various effects and be archived. While the effect seems similar to images complete out of focus there are distinct differences. With soft focus control over the depth of field can be used in the image while with out of focus images this is not possible. By not cleaning finger marks of the lens, many photographers produce soft focus images without trying.
Depending on the subject material, soft focus images tend to relate ideas of dreaming, the romantic, the ephemeral and atmosphere.