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Information types and topics
Topics are the building blocks of modular documents, and organising topics by semantic information types is one of the architectural features of DITA.
What is a topic?
A topic in DITA is an independent chunk of information covering a single idea or task, authored as a unit, and stored in its own file. Topics are categorised by information type. DITA's topic-based architecture enables the same topic to be used in different publications.
Chunking information into topics
Documents can be broken down into smaller chunks of content that can be treated as modular building blocks. Chunks should be organised into separate topic files.

Introduction
Information types and topics
Topics are the building blocks of modular documents, and organising topics by semantic information types is one of the architectural features of DITA.
- Content models and information types
  A content model is a framework that represents the structure of the information to be stored. In DITA, a content model is implemented as an information type, or topic type.
- Information types
  A fundamental principle of DITA is information typing, which categorises information according to the nature of the content. The three base DITA information types are concept, task and reference.
- What is a topic?
  A topic in DITA is an independent chunk of information covering a single idea or task, authored as a unit, and stored in its own file. Topics are categorised by information type. DITA's topic-based architecture enables the same topic to be used in different publications.
  - How detailed should a topic be?
    A DITA topic should be as short as possible, but as long as is necessary to convey its information independently.
  - Granularity - one file per topic
    DITA topics should be saved as individual files, and the ditabase composite topic should be avoided.
  - Chunking information into topics
    Documents can be broken down into smaller chunks of content that can be treated as modular building blocks. Chunks should be organised into separate topic files.
  - Avoiding chunk structure in topics
    The hierarchy of information chunks, and the sequence that chunks should appear in published collections, should be defined in the ditamap and not through section elements or nested topics.
- Working with topics
- Specialised information types
  Specialised information types provide a topic architecture that closely matches the structure of your content.
- Topic exemplars
DITA map files
Syntax and mark-up
Language and punctuation
Graphics and figures
Cross-referencing
Cross-references are a means of binding individual topics into a coherent and navigable document.
Content re-use
Metadata, conditional processing, and indexing
The DITA documentation process
DITA authoring concepts
Moving from style-based authoring to a structured authoring methodology such as DITA requires a radically different approach to writing.

Chunking information into topics

Documents can be broken down into smaller chunks of content that can be treated as modular building blocks. Chunks should be organised into separate topic files.

With topic-based documentation, the way in which information is broken down and chunked into topics is very important. A user guide with one very long topic organised into sections is poorly chunked. Topics should be small, self-contained, granular units of content. In general, the smaller the topic size, the greater the chance that topic can be re-used in another deliverable document.

The process of chunking involves analysing the components of the information to be documented, identifying the blocks of content that can stand alone as information units, and then splitting those units into separate chunks.

In DITA, standalone chunks can be organised into topics, sections within topics, or topics within topics. You should aim to have separate topics for each chunk, and to avoid sections and composite topics.

Information in a DITA source topic doesn't have to be delivered at the same granularity. For example, a family of DITA topics may be output as a single HTML topic. (The chunking attribute in the topicref element in the ditamap is used for this purpose.)