Techniques are described for identifying potentially interesting portions of a content item to be provided as a preview of the content item for prospective purchasers, based on previously collected data associated with the content item. Portions of a content item may be identified as potentially interesting based on a number of annotations (e.g., highlights, bookmarks, notes, and shares) previously made by viewers of a digital version of the content item. Potentially interesting portions may also include portions which prior viewers spent more time viewing, portions related to identified interests of the potential buyer, portions that are identified as separable for particular categories of content, and/or portions that have been previously identified as associated with elements of the content such as character, plot, and/or keywords.