Who can simply say what a chord is?

To put it simply: three or more different sounds are combined together according to certain rules and pronounced at the same time, which is a chord.

In European classical music, the adjacent notes in a chord are all three-degree intervals.

In China's music, chords do not always follow a three-dimensional relationship.

In European music, three-tone chords are called triads, four tones are called heptachords (the lowest and highest tones are separated by seven degrees), five tones are called nine chords (the lowest and highest tones are separated by nine degrees), and so on. The pianos that beginners often encounter are classified according to their names:

Trichord in major. The structure is the root (the chord with the lowest original position) and the alto are three degrees higher, the alto and the highest note are three degrees lower, and the bottom-up is three degrees higher and three degrees lower. Such as do, mi and sol chords.

Minor chords. Roots and alto are minor, and alto and treble are major. It's three degrees+three degrees from bottom to top. Such as la, do and mi chords.

Subtractive triad, root to middle, middle to top are minor degrees, and from bottom to top are minor degrees+minor degrees. Such as si, re and fa chords.

The notes at both ends of the major and minor chords form a pure fifth interval, while the two notes of the minus triad are minus five degrees.

It belongs to the seventh chord. If you add a minor third to major triad, the root and the highest note form a minor seventh-degree interval, which is the seventh chord. Such as sol, si, re and fa chords.

These are the original forms of chords. In addition, there are chord transposition, ellipsis, dense arrangement and open arrangement.

The above are classified by name. For example, according to the classification of playing techniques, there are: long-lasting chords, Legato chords, Non-Legato chords, Jumping Chords, Explosive Chords, and the same chord that keeps repeating.