变成 (biàn chéng) is a compound verb meaning 'to become' or 'to turn into' — indicating a clear change of state, identity, or nature. The first character 变 (biàn) means 'to change', and the second 成 (chéng) means 'to complete' or 'to succeed'; together, they convey the idea of a transformation reaching completion — something has fully changed into something else. It’s commonly used for concrete, observable changes (e.g., ice turning to water) as well as abstract shifts (e.g., a hobby becoming a career).

This verb always takes a subject and an object or complement: Subject + 变成 + [new state/identity]. It does not take aspect particles like 了 or 过 directly after it (they usually appear before or after the whole phrase), and it’s neutral in register — suitable for both spoken and written Chinese. Unlike the stative verb 是 (shì), 变成 emphasizes process and transformation, not static identity.