Data Mapping
Mapping to a single asset using the Asset Name field
Data mapping is done through the Asset Name field and the mapping field for a specific component. The Asset Name field is a cascading field, so each component will check if an id is assigned, and then look to its parent for and id if it doesn't find one. In this way, a single id can be set at the parent level and applied to many child components. See this video for an explanation of this concept.
Dynamically mapping based on a tag
Using a similar concept of the data mapping to a single asset, you can also use a component which uses a filter based on a tag to dynamically create components. For example, the List component and NavGroup components both use tag filters to create a list of assets or a group of pages. See this video for an explanation of this concept.