Topdown

Topdown, typically written as top-down or top down, is a term used across multiple disciplines to describe processes or perspectives that start at a higher level of abstraction and cascade down to detail. It is the counterpart of bottom-up approaches.

In management and design, top-down approaches begin with strategic goals or system requirements and decompose them into tasks, components, or modules. This can improve coordination and alignment but may limit flexibility and local optimization.

In computing and information processing, top-down describes methods that start from a high-level structure. Examples include top-down parsing in compilers, where a start symbol expands to the input, or top-down design where software architecture is established before implementation. The concept also appears in AI planning and problem solving, where overall goals guide the search for solutions.

In cognitive psychology and perception, top-down processing refers to using prior knowledge and expectations to interpret sensory input, contrasted with bottom-up, data-driven perception. In graphics, photography, and games, a top-down view provides a vantage point from above, commonly used for strategy games, maps, and surveillance-style imagery.

In administration and budgeting, top-down planning or budgeting allocates resources from a central authority to lower levels, often aiming for uniform standards or centralized control. The term remains common in theory and practice across fields, reflecting a hierarchical orientation in how problems are approached and solved.