An Introduction To Digital Preservation
About This Document
This briefing document provides an introduction to digital preservation.
What Is Digital Preservation?
Digital preservation is the management of digital information over time. It takes the form of processes and activities that ensure continued access to information and all kinds of records, both scientific and cultural heritage, that exists in digital form.
The aim of digital preservation is long-term, error-free storage of digital information, with the means of retrieval and interpretation, for the period of time that information is required.
Why Do We Need Digital Preservation?
The digital world is a place of rapid technological and organisational changes, which impacts on the continuing use of digital resources. In contrast to our physical written heritage, still readable today, digital information created only a few years ago is in danger of being lost.
Which Materials Need Preservation?
All types of digital resources need preservation including:
- Digitally Reformatted
- Digitised versions or surrogates of physical items.
- Born Digital
- Digital resources that have no analogue counterpart.
- Individual resources
- Texts, still and moving images, sound recordings, etc.
- Collective resources
- Web sites, e-journals, wikis, catalogues, etc.
- Data Sets
- Scientific and cultural data comprising multiple individual pieces of data.
- Communication record
- For example, email, instant messages, etc.
Preservation Metadata
The long-term storage of digital information is assisted by the inclusion of preservation metadata which records various features of the resource. For example:
- Format
- MS Word or Notepad? MS Word 2 or MS Word 6? JPEG or GIF?
- Version
- Pre-print, published.
- Playback
- Equipment or emulation device required.
Issues
Digital preservation encompasses a range of strategies, processes and activities, with a variety of associated issues to be considered. Examples are:
- Long-term
- May extend indefinitely and depends on the need for continuing access to a resource in one or more specific formats. The lifetime of a specific resource is determined by the degradation and/or format accessibility of that resource.
- Retrieval
- Obtaining digital files from storage without corrupting the stored files.
- Interpretation
- The digital files must be decoded and transformed into usable representations, for machine processing and/or human access.
- Rendering
- Making a digital file available for a human to access.
- Re-digitising
- Some early digitised resources are in formats that are, or are rapidly becoming, obsolete. Since it can be the case that poor results are obtained by migrating from the obsolete format to a newer format, it may sometimes be better to re-digitise from the original.
- Emulation
- Where specific playback equipment is no longer available, emulation software may need to be written in order to access the informational content using a different device.
- Degradation
- The process by which parts of a resource are lost over time. This may occur as a characteristic of a format (it becomes a less accurate representation over time) or a consequence of copying from another file or migrating from one format to another.
- Effort
- It appears that digital preservation requires more frequent and ongoing action than other types of media. The consequent requirement in terms of effort, time and money is a major stumbling block for preserving digital information.
