It's a combination of several things. Light and composition are two of the biggest things... the subject matter can make a difference, too, although a good photographer can often take the most ordinary thing and turn it into something spectacular.
More than anything though, I think it's the photographer's ability to draw the viewer into the photograph. Something needs to grab your attention and hold you there to make it a truly good photo. This can be done through composition, subject matter, style, color, anything and everything, really.
By making objects close with more detail, and objects far away with less detail
Answer with Explanation:
You have not included the image so I have done quick google search and I am putting the image that matched with the same worded question I found.
The question is (hopefully) about the Image "Morning View of Nihonbashi" by Utagawa Hiroshige.
As with any art, some aspects of the answer are subjective and will vary from observer to observer. First let's discuss about some details related to the scene. This is an Asian artwork, particularly a Japanese ukiyo-e scene. The scene can be interpreted as two groups of men, walking in two rows, moving goods across a bridge. One group is carrying some sort of cargo in boxes while the other group is carrying baskets of food. Some houses can also be seen in the background. The sky colour depicts a sunset with reddish-yellow tones.
Speaking of tones, orange, blue, and yellow are the primary colors used. The artist has used thin lines throughout the scene. Fairly simple geometric shapes are used. The scene is enclosed by the use of a gate or fence.
This is a typical example of a woodblock print, also called a woodcut, it was a technique used widely throughout East Asia. The corners of the woodblock were used as the registration points.