The document summarizes the Open Annotation Collaboration (OAC) Model which aims to enable sharing of annotations across platforms and content collections. It presents the OAC goals, the baseline data model where an annotation associates a body resource about a target resource, additional properties that can be included, different annotation types, how bodies can be embedded inline, and how fragments and media fragments can identify portions of resources. It discusses how constrained targets can describe segments that can't use fragment URIs.