Symmetry (ancient Greek proportionality; from jointly + I measure) , in a broad sense - conformity, immutability (invariance), manifested with any changes, transformations (for example, position, energy, information, other). For example, the spherical symmetry of the body means that the shape of the body will not change if it is rotated in space at arbitrary angles (keeping one point in place). Bilateral symmetry means that the right and left side relative to any plane look the same.
The absence or violation of symmetry is called asymmetry or arrhythmia. General symmetry properties are described using group theory. Symmetries can be exact or approximate.
We have always been obsessed with symmetry, starting with an ideal-shaped fruit, and ending with the impeccable Vitruvian Man by Leonardo da Vinci. The Symmetrical Monsters ("Symmetrical Monsters") page on Instagram is a real treat for every perfectionist, because it is replete with all sorts of examples of symmetrical architecture.