A content reference (conref) is used to create a reference to content (elements) from a DITA topic or DITA map in another DITA topic. Using a conref you can reuse content (elements) across DITA topics. A conref is based on the DITA ID attribute assigned to the element. This implies that if the position of an element in the topic changes, the reference remains intact as long as the ID remains intact.
You can use direct referencing to point directly to the DITA topic (.xml file) containing the target topics or elements. Alternatively, you can use indirect referencing to point to keys defined in keyspaces. For more details, see DITA referencing.
You can create conrefs for almost any element in the DITA element catalog. You create conrefs for a DITA topic to make an entire topic reusable. You can also create a conref for a keyword or ph element to reuse a term or even word. The only requirement to create a conref is that the element must define the DITA ID attribute.