You can take a look at a picture and fall in love with it without any special reason. After a while you’ll start thinking what made me fall in love with it? There isn’t anything extra special so is it’s composition? Subject? Anything else? Sometimes it is a mood in the image. You can feel it but it is hard to describe. Of course it isn’t always there but you can create it using light or even post processing. But believe me, not every time it works perfectly.