This is one of the easiest and most transformational photo compositional techniques.

Firstly, what is composition? Your image includes the main subject and extra elements in the frame. The composition is how elements are positioned and how they all interact with each other. 

Rule of Thirds is the process of placing two equally spaced vertical and horizontal lines across the photo. This creates nine squares, looking like a Tic-Tac-Toe board. 

In your camera setting turn on the Grid or Gridlines. The idea is to place the main subject on top of one of these lines effectively placing it off-centre. The result is a more dynamic-looking image instead of the subject static in the centre of the frame. This also creates space around the subject for the viewer's attention to explore other elements in the scene.

Activity objective: Composition is the first step to becoming a more intentional storyteller.

Tip: The sweet spot is placing your main subject on one of the four points where the lines intersect. Your subject will then be off-centre both vertically and horizontally.