Progressione

Progressione is a term used in Italian and other languages to denote the act of progressing or a sequence that advances according to a rule. The word derives from Latin progressio, from progredi, meaning to go forward.

In mathematics, a progression (also called a sequence) is an ordered list of elements defined by a rule. The most common types are arithmetic progression, where successive terms differ by a constant difference; geometric progression, where each term is a constant multiple of the previous; and harmonic progression, in which the reciprocals of the terms form an arithmetic progression. Examples include 1, 3, 5, 7 as an arithmetic progression with difference 2, and 2, 6, 18, 54 as a geometric progression with ratio 3.

In music, progressione refers to a harmonic progression, the sequence of chords that underpins a passage and guides tonal direction toward a cadence. Familiar progressions include I–IV–V–I in major keys.

More broadly, progressione can describe the course of a process or development, such as the progression of a disease, a project, or a narrative arc, where states change step by step over time.

In Italian, progressione covers these senses; in English, the term progression is usually used, with discipline-specific terms such as harmonic progression in music or sequence in mathematics.