Tween

Tween is a term with multiple meanings across fields including animation, childhood development, marketing, and software. The common thread is the concept of "between"—whether between keyframes, between ages, or between stages of growth. The word's usage varies by context, and its exact meaning is defined by the domain in question.

In animation and computer graphics, tweening or in-betweening is the process of generating intermediate frames or states between two keyframes or key states. It provides smooth motion or transitions without manual drawing of every frame. In traditional animation, artists drew in-between frames; in digital tools, algorithms interpolate positions, shapes, colors, or properties over time. Tweening is central to many animation techniques and is commonly implemented in animation software and libraries.

In popular usage, Tween refers to a demographic group of children aged roughly eight to twelve who are between elementary school and adolescence. Tweens are targeted by a distinct range of media products, toys, clothing, and content. The term stresses a transitional phase marked by rapid social, physical, and cognitive changes, though individual development varies widely. The concept informs both educational approaches and consumer marketing strategies.

In software development, the term tween describes a software object or function that performs interpolation between values, such as positions, scales, colors, or other properties. Tween libraries and frameworks facilitate smooth transitions in user interfaces and games. The concept is also common in web animation, often implemented through dedicated libraries that manage easing, duration, and chaining of multiple tween steps. The etymology traces to "between," reflecting the generation of the in-between state.