The Rule of Thirds is a rule that suggests that cinematographers and photographers should think of their shots as being in thirds, both vertically and horizontally, like in the animation below.
Source: Moondigger [CC BY-SA 2.5], via Wikimedia Commons
The rule states that the most important features of a shot should be either along these imaginary lines, or potentially at the intersections of the lines. This will make for the most aesthetically pleasing and balanced shots.
Alongside the Rule of Thirds is the idea of Central Framing, where a character or object is placed in the centre of the frame…or where the centre of the frame is used to separate two distinct sides of the shot. These shots often utilise symmetry on either side of the frame.
To firm up your understanding of both of these techniques, check out the two videos below – the first from filmmaker Philip Bloom, and the second from YouTuber D4Darious:
For those of you who are interested, you can see examples of Central Framing from two famous directors below:
Other Shot Composition pages on Opening Class:
Shot Composition For Your Film