3categories

3categories is a term used in several disciplines to denote a three-way classification framework. It does not refer to a single fixed theory, but rather to a model that partitions items into three mutually exclusive categories that collectively cover all possibilities. The exact meaning of the three categories varies by context, but the common thread is the triadic structure rather than a binary or multi-way scheme.

In machine learning and information organization, 3categories often appears as a three-class classifier or taxonomy. Items are assigned to one of three labels, which may be simple groupings such as positive, neutral, and negative, or domain-specific categories such as primary, secondary, and tertiary. In linguistics and cognitive science, the term can describe triadic typologies or feature sets that distinguish three opposing or complementary states. In software design and data management, it is sometimes used as a naming convention or schema for a tri-level hierarchy, status flag, or access-control tier.

Because the label is generic, different sources may define the three categories differently and may incorporate ordinal versus nominal distinctions, probabilistic interpretations, or decision thresholds. When encountering the term, it is important to consult the original source to understand how the three categories are defined and applied within that particular framework.

See also: Three-class classification; Taxonomy; Classification (sciences).