In DITA XML, links are a fundamental mechanism for connecting and organizing content within and between topics. They allow for seamless navigation and the creation of an interconnected documentation structure. Links in DITA serve several important purposes:

1. Cross-References: DITA cross-references link to other topics or sections within the documentation, enabling readers to navigate between related content. This is particularly useful when a topic references or builds upon information covered in another topic. Here’s an example of a DITA cross-reference:

<!-- Example: DITA Cross-Reference -->
<ph><xref href="related_topic.dita"/></ph>

2. References to Key Definitions: DITA key references link specific terms within a topic to their definitions or extended descriptions, often found in a glossary or dedicated reference section. Readers can access these definitions by clicking on the linked term. Here’s an example of a DITA key reference:

<!-- Example: DITA Key Reference -->
<term keyref="term_definition_key">Key Term</term>

3. Links to External Resources: DITA supports links to external resources, such as websites, documents, or online references. These links provide additional context or direct readers to external sources for further information. An example of an external link in DITA is as follows:

<!-- Example: DITA External Link -->
<ph><xref href="https://www.example.com"/></ph>

By using these types of links, DITA allows for a flexible and organized approach to creating content, ensuring that readers can easily explore related topics, access definitions, and refer to external resources when necessary.