Increasingly publishers, trainers and corporates are switching from local, offline-based document viewing systems to online, i.e. web-based solutions and services. These offer the possibility of displaying a range of document formats and media types, using standardized HTML5-compliant web browsers. This obviates the need to download any software or document files, and provides for simple, fast and scalable access to end users, with minimal support and service management requirements. There are limitations to such systems of course, for example they cannot offer as much security of content as offline systems, and the level of some functionality and interaction is often limited, but the technology in this area is developing rapidly.
In general there are HTML5-based viewers for most of the widely used document formats, including PDF, ePUB, and MS Office Documents (Word, Powerpoint). In many instances the source documents are provided just for display (viewing, reading) but sometimes printing and downloading are permitted. The latter is the norm for PDF files, and many web browsers include a PDF viewer or make the file available for download to be viewed and optionally printed by an offline PDF viewer.
Within the web-based document display facility a range of approaches are used to present the document content. In some cases the documents are dynamically converted to an HTML5 compliant format, whereas in others they are statically converted in advance. The latter is faster for end users and can provide a higher quality result, depending on the conversion procedure adopted. Some online services convert source material into images of pages, rather than attempting to replicate the source presentation including scalable fonts and graphics - the latter obviously provides a much better and more scalable display, and offers the potential for full text searching with highlighting, plus markup and improved accessibility.
On top of the display layer, services may provide a range of additional functionality, including Digital Rights Management (DRM), e-Commerce, Document sharing, Markup/Annotations, integration with other systems and technologies (e.g. smart teaching systems).