A core strength of the Campaign Manager framework is that nothing is wasted. In all areas you can save and re-use objects by turning them into templates - from simple segments to Output Layouts and even Campaign Tactics. If you are unsure, you can always right click on an object and there will inevitably be a 'Save as Template' option.
Templates are stored as documents within the document
storage structure, with Templates having a '+' icon to distinguish them
from 'normal' documents when accessed from the Document Explorer, for
example 
.
Template documents can be opened in three ways:
From the Document Explorer, where you can select the [Open] button to open the actual template (administrators only), or the [Open Copy] button which will create a clone of the template that you can then edit without affecting the original. At this point, the link with the template is broken and any subsequent changes to the template will not be reflected in the new document.
From the Templates tab of the Data Explorer Pane. This view shows a subset of the Document Explorer folder structure, but only displays folders that contain templates. Templates can be dragged into documents. At this point a link is created with the original template, and changes to the original template may affect this document.
From the Templates tab of the Data Explorer Pane. This view shows a subset of the Document Explorer folder structure, but only displays folders that contain templates. Templates can be dragged into the Document Bar.. At this point a link is created with the original template, and changes to the original template may affect this document.
Note that the majority of users will use templates created by administrators or power users; they will never need to create templates themselves.