This is a well-known photography principle that is used by all professional photographers. Most smartphone cameras will have an option to view “gridlines”. These lines break an image down into thirds (both horizontally and vertically) so that you have 9 sections.
The theory is that if you place points of interest in the intersections or along the lines, your photo becomes more balanced and will enable a viewer of the image to interact with it more naturally. You may find from viewing your own images that your eyes generally land on one of the intersection points more naturally rather than the centre of the shot. As with all rules, they can still be broken. The Rule of Thirds may not always apply, but it’s there as a helpful guideline. When taking your next photos, try applying this rule and avoid using a centre focus. You can also apply the Rule of Thirds to selfies!
TRY THIS: For your next selfie, see if you can position your eyes or face at one of the points where the lines intersect.