In the realm of music theory, the term "dominant chord" refers to a specific type of chord that plays a crucial role in establishing the tonality and harmonic progression within a piece of music. The dominant chord is typically built upon the fifth scale degree of the diatonic scale, which is why it is often referred to as the "dominant." It is one of the most important chords in Western music, as it creates a sense of tension that is resolved by the tonic chord, thereby reinforcing the key center.
The dominant chord is often a dominant seventh chord, which is composed of a root, major third, perfect fifth, and minor seventh. This chord is significant because it adds an additional layer of tension due to the presence of the minor seventh interval, which is a half step away from the root. This interval is known as the leading tone, and it has a strong pull towards the tonic, creating a sense of resolution when the dominant seventh chord progresses to the tonic chord.
The dominant seventh chord can be represented by the integer notation {0, 4, 7, 10}, which corresponds to the root, major third, perfect fifth, and minor seventh, respectively. This notation system is a convenient way to describe the structure of chords without specifying the actual pitches. For example, if the root is C, the dominant seventh chord would be C7, consisting of the notes C (root), E (major third), G (perfect fifth), and B♭ (minor seventh).
The function of the dominant chord in music is to create a feeling of incompleteness or tension that propels the music forward towards a resolution. This is known as the "dominant-tonic" resolution, where the dominant chord (V) moves to the tonic chord (I). This movement is one of the most fundamental and satisfying in Western music, and it is used to create a sense of arrival or finality at the end of a musical phrase or section.
In addition to its role in creating tension and resolution, the dominant chord also serves as a pivot chord, allowing for smooth modulation to other keys. This is because the dominant seventh chord contains notes that are common to several different keys, making it an ideal chord to bridge the gap between the original key and a new key.
The dominant chord is also used in various chord progressions, such as the ii-V-I progression, which is a common pattern in jazz and popular music. This progression moves from the supertonic chord (ii) to the dominant chord (V) and finally to the tonic chord (I), creating a sense of movement and resolution.
In summary, the dominant chord is a fundamental concept in music theory, playing a vital role in establishing tonality, creating tension and resolution, and facilitating modulation. The dominant seventh chord, with its root, major third, perfect fifth, and minor seventh, is a particularly powerful example of this concept, and its use in music is both widespread and impactful.

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In music theory, a dominant seventh chord, or major minor seventh chord, is a chord composed of a root, major third, perfect fifth, and minor seventh. It can be also viewed as a major triad with an additional minor seventh. ... The chord can be represented by the integer notation {0, 4, 7, 10}.read more >>