Word Automation Services allows performing file operations on a server like conversions between document formats (e.g. DOC to DOCX), converting to fixed formats like PDF or XPS, updating fields, and importing alternate format chunks. It provides server-side rendering of Open XML files into fixed formats with 100% fidelity down to the pixel level. This allows file save as, conversions, and printing operations to happen on the server for high volume throughput and scalability beyond what is possible on individual desktops.