This document discusses social annotation (SA) technologies and practices in writing studies. SA involves adding notes to digital texts for sharing information, peer interaction, knowledge building, and collaborative meaning making. Key SA technologies allow users to annotate web-based texts by selecting text and adding multimedia comments. SA technologies make reading social and interactive by allowing shared access to annotated texts. Research suggests SA supports activities like developing domain knowledge, argumentation, literacy skills, peer feedback, and connecting learning across online spaces. SA also enables reading and writing practices emphasized in process-oriented writing pedagogy.