change

Change is the process by which something becomes different from what it was previously. It can refer to alterations in physical state, structure, position, condition, or identity. Changes occur in natural systems, human societies, technologies, and ideas, and they can be temporary or enduring.

In science, change is described as physical change (alterations in form or state without a new substance) and chemical change (transformations that create new substances). Changes may be reversible, such as phase transitions, or irreversible, such as rusting or breaking a glass.

Changes can be gradual or rapid, local or global. They are often described by measures of difference, such as delta, or by rates of change, such as velocity or the derivative in calculus. In statistics, change is assessed with concepts like trend and regression to distinguish signal from noise.

Across domains, change is driven by causes and mechanisms including natural forces, human action, and feedback processes. Climate change, technological disruption, and social reform illustrate how changes spread through systems and alter futures.

Change management is the practice of guiding groups and organizations through planned changes. It emphasizes leadership, communication, stakeholder engagement, and evaluation to minimize resistance and maximize adaptation and benefits.

Philosophical reflections on change have long debated whether existence is constant or in flux, with ideas from Heraclitus and others shaping perspectives on time, identity, and transformation.