RULE OF THIRDS

The Rule of Thirds is one of the most useful composition rules in photography. Two horizontal and two vertical lines divide your composition into three equally spaced vertical columns and three equally spaced horizontal rows.
To apply this rule, place the main subject and supporting elements of your scene at the intersection of two lines or along a line.
By placing the main subject and supporting elements away from the center forces the viewer's eyes to follow it, adding action and interest, as opposed to a static focus on the center of the photo. In addition, the background will be less obstructed, providing more space for the viewer’s eyes to comfortably rest and explore the photo more interactively.

This icon represented the composition rule on the Wise Camera app and Wise Photos app
★★★★★ Very impressed. This app had way more than I was expecting (Weeman_1)
★★★★★ Helpful for beginners or professionals (Dre9827639)
★★★★★ Can’t find a better composition aid for landscape and travel photography (khl.anthony)