Composition

Rule of Thirds: The rule of thirds states than an image is most pleasing when its subjects or regions are composed along imaginary lines which divide the image into thirds — both vertically and horizontally.
http://www.cambridgeincolour.com/tutorials/rule-of-thirds.htm 

Vertical Composition: A picture that is taken vertically.

Horizontal Composition: A picture that is taken horizontally

Visual balance: A photo that looks balanced.

Symmetrical Balance: All things on one side of the image are mirrored on the other.

Macro: extremely up close photography usually of a small object with the intent that it looks much larger than it actually is.

Landscape: A picture taken outside of nature.

Leading lines: Leading lines are used to draw the viewer’s eye through a photograph.
http://www.photoble.com/photography-tips-tricks/leading-lines-in-photography

The illusion of perspective: technique of manipulating human perception with the help of optical illusion.

Patterns: Patterns, both natural and man-made, bring a sense of visual rhythm and harmony to photographs that, like a series of repeating notes in a melody, capture the 
imagination. http://www.fodors.com/travel-photography/article-patterns-52/ 

Natural framing: Natural framing in photography is a common compositional technique whereby the photographer seeks out natural elements in the environment to serve as frames for the photograph. http://www.craigfergusonimages.com/2010/11/natural-framing/

Shallow depth of field: The subject of the photo is in focus but the background is blurry.

Great depth of field: Everything in the photo is in focus.

Experiment: Experimental photography is using all possible features of one's camera so to fully discover its yield/limits and so to perfect one's field/style. http://artassemblyadvocates.deviantart.com/journal/AAA-Takes-a-look-at-Experimental-Photography-216745834