BRB, let me check my notes on composition, it's not much. There are a handful of rules, and you can immediately say whether a photo is following them or not.
yep
Rule of third - place objects along a third of the screen, either vertically or horizontally or both. Most common mistake here is putting a horizon in the middle of the photo instead of along top third or bottom third, or placing a subject in the center of the photo instead of along the left third or right third. Many cameras have a guide for this rule in the viewfinder itself. This is the most important rule of composition.
Lines and shapes - find patterns, eliminate distractions
Leading lines - lines go away from camera, and direct the eye (eg: shot of a tunnel or corridor)
Symmetry - left and right are same, rule of third not important
Curves - flow from one corner to opposite corner, S shape is good, elongated S shape is best (use when photographing roads)
Balancing elements - no overpowering elements, distribute weight of objects in frame, Large object in foreground can be balanced by small object in background, just imagine a set of scales in the frame and the objects on it. Align objects along opposite thirds horizontally/vertically, or the spots where the 1/3rd lines of the frame intersect.
Viewpoints - bird's eye view, normal eye view, worm eye view. Use according to subject. Small kid then bird's eye view, tall building then worm eye view is standard, switch around for drama.
Traverse - this one is an obscure rule, find something to connect two regions in an image. So sea and sky, find a tree or person to traverse across the two regions or they will appear disjointed.
Background - isolate subject from bg using focus, colour or lighting.
Cropping - remove distractions
but there can be good photos that don't follow the rules, and following the rules is no guarantee of good photos.