Central Composition
Placing the primary subject at or near the centre of the frame.
In depth
Centring is often taught as a beginner's mistake, but it is a deliberate device with its own character: it is confrontational, formal and static, and it removes any suggestion of narrative direction. It suits symmetry, portraiture that meets the viewer's gaze directly, and any subject whose meaning is its own presence rather than its relationship to surroundings.
Examples in practice
A head-on portrait with the eyes dead centre reads as direct and formal in a way an off-centre placement would soften.