Separation of presentation and content

Separation of presentation and content (or "separate content from presentation") is a common idiom, a design philosophy, and a methodology applied in the context of various publishing technology disciplines, including information retrieval, template processing, web design, web development, word processing, desktop publishing, and model-driven development. It is a specific instance of the more general philosophy, separation of concerns.

Intended meaning

When invoked as an idiom, the underlying concept is represented with varying levels of precision and with differing connotations. Some apply the concept prescriptively (reductionism), others use it heuristically or didactically. Sometimes the intended meaning is left unclear or is entirely subjective.

The varying levels of precision applied to this concept is sometimes the source of some confusion, contradiction, and trial and error. This makes it difficult to specify conclusively when (or if) the philosophy is successfully fulfilled for any given implementation (see also, leaky abstraction).

Semantics vs. aesthetics

Generally, the concept of separation is based on the distinction between semantic content and aesthetic presentation. It is not always possible to determine an exact boundary that separates these two dimensions, which is why the distinction is applied with varying degrees of rigor in different contexts. One rationale supporting this demarcation is the opinion that each dimension should be flexible and independent. Changes in one aspect should not necessarily require changes to the other; defects in one aspect should not introduce defects in the other (see e.g., loose coupling).

Common terms

There are a number of common terms used to describe these two separate dimensions of content, which include:

Semantic

logic, information, ontology, semantics, data, outline, model, message

Aesthetic

graphics, design, layout, style, visualization, view, medium

Possibility and degrees of separation

In communication design, the message is the content and the medium is the tools to deliver that message. In the book Understanding Media, Marshall McLuhan stated that "The medium is the message", which has since been the subject of much debate. One interpretation is that the choice of medium (presentation tools) affects the (presentation content) message. It is possible for the choice of content and choice of medium to affect the quality of the presentation, meaning how well a message may be received. The degree that content may be separated from presentation depends on how much the quality of the medium effects the quality of the message. In many cases, the possibility and degrees of separation are as subjective as the content itself.

See also

• Separation of concerns
• Templates
• Style sheet (web development)
• Style sheet (desktop publishing)
• Template systems
• What You See Is What You Mean
• Internationalization
• model-view-controller

External links

• CSS Zen Garden: A site which challenges designers to create new page layouts without touching the XHTML source. Includes dozens of layouts. CSS source can be viewed for every layout.