Harmony comes from the Latin harmonĭa, which derives from the Greek ἁρμονία , which means agreement, concordance, combination, and the verb ἁρμόζω (harmozo), which means to adjust, connect.
Harmony occurs when there is a balance and a convenient and adequate proportion, concordance and correspondence of some things with others, and where appropriate, pleasing to the senses, for example, to the eye, such as colors. Something in harmony is usually something really beautiful, cheerful, pleasant, relaxing and peaceful, although in music, for example, there is also harmony that produces tension, or is dissonant.
In music, especially in western music, harmony is the art of uniting and combining different sounds, but consistent and pleasing to the ear, which are emitted simultaneously.
It is also called harmony to science, technique and discipline that allows both the formation, succession and modulation of the chords (combination of three or more different notes that sound simultaneously or in an arpeggio), such as the chaining and combination of these forming a musical composition.
The harmony works as accompaniment, frame and base of one or more melodies.
In the literature, harmony is called the pleasant variety of sounds, pauses and measures that results in both verse and prose for the proper combination of syllables, voices and clauses used.
The expression ‘have harmony with’ or ‘live in perfect harmony’ can mean having an agreement, a good friendship or relationship, a relationship of peace, good communication and good correspondence or compatibility of opinion and action with someone or with a group.
However, the concept of harmony depends on each culture and each era, that is, what was harmony in the second century, may not be in the twentieth century and what is harmony in China, may not be in Spain.