Model

A model is a simplified representation of a real object, system, or process that is used to explain its behavior, test ideas, or make predictions. Models abstract away irrelevant details to focus on essential features, allowing researchers and designers to reason about complex phenomena without direct experimentation. Models can be physical, mathematical, computational, or conceptual, and they are valued for their explanatory power and versatility.

Physical models include scale replicas of machines, buildings, landscapes, or prototypes used in engineering and design. Mathematical models express relationships with equations or rules, such as differential equations describing motion, population dynamics, or chemical reactions. Computational models implement mathematical descriptions in software to simulate large or intricate systems. Statistical models use data to estimate relationships and uncertainties, including regression, time-series analysis, and probabilistic frameworks.

Validation and calibration compare model outputs with real-world data or experiments. A model is judged by predictive accuracy, robustness to parameter changes, and the transparency of its assumptions. All models are deliberate abstractions; their usefulness depends on the relevance of the assumptions and the quality of the input data. Limitations include measurement error, missing factors, and scale differences between model and system.

In everyday language, model may also refer to a person who poses for artists or fashion photography, or to a preliminary design used to illustrate a concept. In science and engineering, models serve as tools for understanding, planning, and decision making, from climate projections to product development.

Etymology: from Latin modus or modulus, via Old French modele, meaning measure or form.